The NLM Catalog provides access to NLM bibliographic data for over 1.2 million journals, books, audiovisuals, computer software, electronic resources, and other materials via the NCBI Entrez retrieval system. The Entrez retrieval system was developed by the National Center for Biotechnology Information (NCBI) at the National Library of Medicine, located at the National Institutes of Health (NIH). Entrez is the text-based search and retrieval system used at NCBI for services including PubMed, Journals, OMIM, Nucleotide and Protein Sequences, Protein Structures, Complete Genomes, Taxonomy, and others.

Updated every weekday, the NLM Catalog is an alternative search interface to the bibliographic records resident in LocatorPlus. For complete information regarding NLM's holdings and an item's circulation status, visit LocatorPlus .

To begin:

• Simple searching - enter your term(s) and click GO. Entrez automatically combines (ANDs) significant terms together.
• Phrase searching - enter your phrase in quotes
• Searching of specific fields by use of Limits (e.g., limit retrieval to a particular language, material type, date, etc.)
• View how your term(s) were searched using Details
• View and reuse previous searches using History
• See the library's holdings in LocatorPlus, NLM's online public access catalog by clicking on the NLM ID or using Links (located to the right of each result).

Enter one or more search terms in the query box and press the Enter key or click Go.

Search terms may be entered in upper or lower case. The NLM Catalog ignores most punctuation entered for searching. The Features bar beneath the query box provides access to additional search options.

• Operators must be in upper case (e.g., AND).
• The default operator is AND.
• All operators are processed in a left-to-right sequence.

Note: To change the order in which the operators in a search statement are processed, enclose search terms in parentheses (Nesting). The terms inside the set of parentheses are processed as a unit and then incorporated into the overall search strategy.

Subjects in NLM Catalog records include Medical Subject Headings (MeSH) terms, Personal Names, and Other Subjects.

NLM's Medical Subject Headings controlled vocabulary of biomedical terms that is used to describe the subject of each journal article in MEDLINE. MeSH contains more than 23,000 terms and is updated annually to reflect changes in medicine and medical terminology.

To search a MeSH term enter the term, followed by the field qualifier [mh].

To search a MeSH term with one or more subheadings, enter the term, a forward slash, and one subheading, followed by the field qualifier. Multiple subheadings are ORed together.

A MeSH term may be one of the main topics discussed in the item (MeSH Major Topic).
Enter the MeSH term followed by the field qualifier ([majr]).

MeSH terms are arranged hierarchically by subject categories with more specific terms arranged beneath broader terms. Each term has a tree number that positions the term in the hierarchy.

Eye [A01.456.505.420]

Eyebrows [A01.456.505.420.338]

Eyelids [A01.456.505.420.504]

Eyelashes [A01.456.505.420.504.421

By having narrower terms indented under broader terms, a search of a broad term can automatically include the narrower terms. When a term is searched as a MeSH Heading, NLM Catalog automatically searches that heading and the more specific headings underneath in the hierarchy. This is called exploding a term.

Enter a personal name following the format for searching an Author Personal Name. Qualify the name with the Personal Name as Subject or Personal Full Name as Subject. The qualifiers [ps] and [fps] are also available.

Subject terms that are not MeSH or Personal Names are in the Other Subject(s) field. Enter the term followed by the field qualifier [ot].

Unqualified search terms are processed using Automatic Term Mapping. The term is matched against a MeSH Translation Table. If a match is found, the term is searched as a MeSH term and as a text word.

If no MeSH match is found, the term is matched against a Journals Translation Table and then an Author Index. If there is no match, the term is searched in All Fields.

Searching Tip: Click on Details to verify how the search query was translated

When a phrase is entered as the search term, it is checked against the translation table that is used in Automatic Term Mapping. When a match is found, it is searched as a multi-word search term.

When a phrase is not automatically identified in the table, you can request a check for the phrase in the NLM Catalog's index of searchable terms. Either enter the phrase in quotes, e.g., "single cell," or qualify the phrase with a search tag, e.g., single cell[ti]. When a phrase in double quotes is found in the index, it is searched as a multi-word search term and automatic term mapping is not applied. There is no explosion of MeSH terms.

Note: If your search phrase is not in the index of searchable terms, the individual terms in the phrase are processed using automatic term mapping and all terms are ANDed together.

Send suggestions of phrases to add to this index to NLM Customer Service.

Narrow your search to specific fields by adding the Search Field Label or Tag after the search term.

Note: Enclose the Label or Tag qualifier in brackets. The qualifiers can be in upper or lower case (all examples given in help use lower case).

Enter one or more words from the title, with each word followed by the field qualifier [ti].

You can search for either the name of an individual author (Personal Name) or for the organization (corporate name) or conference which is considered the author of a work.

There are several different options for searching for personal author names.

Enter the name in the format of last name and up to the first two initials (no punctuation).

A name entered using this format initiates a search of the author field. The NLM Catalog automatically truncates the author's name to account for varying initials and designations such as Jr or 2nd. For example, miles m matches miles m and miles ma, miles mf, miles mt, etc.

Enter the last name qualified with the author tag [au].

Enter the Full Author Name. Use of the search tag [fau] is not required. Unlike conventional author searching (e.g., smith js), full author searching can be in either natural or inverted order.

When searching a full name using the inverted order, a comma following the last name is generally optional, remove periods after initials, and put all suffixes, e.g., Jr, at the end. For example, to search for the author Anthony S. Fauci, you may use any of the following formats:

• fauci, anthony s
• fauci anthony s
• anthony s fauci

Although the comma following the last name is generally optional, for some names, it is necessary to distinguish which name is the last name by using the comma following the last name.

Full author name searching allows for automatic truncation of the forename. If you don't know the middle initial, do not use the truncation symbol, enter only the last and first names.

Names with multiple middle initials, e.g., Stanley P L Leong, have a space in between the initials. Using the examples listed below will retrieve the expected results.

Caveat for searching Full Author Name

If the first and middle names consist of only initials it is best to search as for author, using the last name and the first and second initials, without a comma between the elements. The use of the qualifier [au] is optional.

• Enter the name, without punctuation, qualified with the corporate/conference author tag [cn].

• Use "Index" in Preview/Index to determine specific spelling for corporate/conference names.
• Authorized forms of names may be found by browsing name and title headings in the Authority Index.

• Provides access to an index of full author names (including dates and name qualifiers), organizations, conference names, and series titles, associated with the bibliographic records in the NLM Catalog.
• Offers added value by incorporating rich cross-reference entries for variant forms of names (includes personal, corporate or conference names) and titles that lead the user from a raw, initial search to the established form used on bibliographic records in the NLM Catalog.
• Supports searching of names that may have changed over time, providing links to other and historical names used by authors or organizations and to conference names and series titles that have changed numerous times. For series titles, additional information regarding NLM's bibliographic treatment of that series is also provided (see Display of Series Information below).

Click on the new Authority Index tab that appears to the right of the "Details" tab. Enter the name (includes personal, corporate or conference names) or series title as an unqualified search in the new search box that is displayed. Click the box labeled "Search" to invoke the search of the index.

Optionally, enter a name of a person, organization, conference, or series title into the main search box, qualified by [ai]. When this is done, the system automatically invokes the "Authority Index" tab and the search also appears in the authority index search box.

A search of the authority index results in an alphabetic display. The established form of the name is hyperlinked; clicking on this link retrieves the bibliographic record(s) associated with that name in the NLM Catalog.

The advantage of a search of the authority index is that it provides for more specificity in a search. As an illustration, using the authority index results in retrieval of a single bibliographic record associated with the name "Smith, J Barker" whereas a search of the name as an author yields twenty-six (26) bibliographic records that need to be examined to determine the one desired.

The authority index also provides access to cross-reference entries for variant forms of names and titles that can assist the searcher in identifying the form used in NLM bibliographic records and improve the success and exactness of retrieval. Additionally, links are provided to the different forms of a name or series title that may have changed over time.

• Searching Variant Forms

Variant forms appear before the word "see", appear in black type, and are not hyperlinked. The user is led from this other, variant form to the established form of the name (appearing after the word "see") that is hyperlinked. When a user clicks on the hyperlink for the established form, that form appears in the authority index search box and at the top of the authority index. Clicking once again on the established form in the authority index retrieves all bibliographic records associated with that established name.

• Using Links to Other Forms

The authority index also provides links to earlier, later, and related forms of names and titles, identified by the label "see also." These "see also" entries provide links to other names used by persons over time, historical names of organizations, and changes in titles of series.

All established forms used by the organization appear after the phrase "see also" and are hyperlinked. Clicking on these established forms leads the user to the bibliographic records associated with those names or titles.

When a series title is searched in the authority index, the display of the series title is prefaced by a plus sign (+) and the label "Series: ," with the title of the series appearing alphabetically.

Clicking on the plus sign reveals additional information related to the NLM treatment of that series title. The information provided includes the NLM analysis practice, classification practice, and classification number (when present). These data appear labeled as:

• New and changed authority information is added to the NLM Catalog on a weekly basis; therefore, the search results may not be comprehensive.
• When an authority index search is performed using the main search box and the qualifier [ai], the system automatically invokes the "Authority Index" tab, so that the search also appears in the authority index search box. Here, either pressing the enter key or clicking "Go" invokes a search.
• When using the authority index search from the "Authority Index" tab, click the “Search” button.
• To inactivate the "Authority Index tab," click "Go" next to the main search box.
• When the desired established form is selected from the authority index, the system automatically enters a number with the qualifier for the authority index id number [aiid] in the main search box.
• The "Details" tab contains the authority index id number [aiid] for the search, not the literal of the name(s) or series title(s) that the user has entered.
• When searches are done against the authority index, the "History" tab contains the trail of authority index id number(s) [aiid] retrieved and it is not possible to view the history of the names or series titles searched. As for other searches in the NLM Catalog, the number in the "Results" column refers to the number of bibliographic records associated with that authority index id [aiid].

For detailed information see the NLM Technical Bulletin.

Truncation or wildcard searching allows you to search a root word and all of its variations that might prove valuable to your search (for example, using 'flavor' to find all terms that begin with flavor: flavored, flavorful, etc.).

• Place an asterisk at the end of a term to search for all words that begin with it, e.g., flavor* to find flavor, flavored, flavorful, etc.
• This truncation feature is limited to the first 600 variations found. If the search retrieves more than the 600 variations, you will be shown the following warning message:

Wildcard search for term* used only the first 600 variations.
Lengthen the root word to search for all endings.

Note: Truncation turns off automatic term mapping and automatic explosion of a MeSH term.

Use this feature to find the citation for any resource in the NLM Catalog (e.g., book, book chapter, audiovisual material or serial).

• Enter information in any or all of the search boxes.
• For author, enter the name in the format last name and up to the first two initials (no punctuation).

Examples:
remington j
miller sd

Note: You can also search using full author name in the Single Record Matcher

The following search features are located on the NLM Catalog Features bar.

This feature limits or restricts your search by:

• Language
• Publication Type
• NLM Collection
• Full Text
• Publication Year
• Material Type
• All Fields

The feature provides a list of the most frequently searched languages.

You may also search for a language by entering the language name in the query box and qualifying it with the search field tag [la].

The complete list of languages used is based on the official list of languages provided in the MARC Code List of Languages, a standard maintained by the U.S. Library of Congress.

The pull-down menu contains a list of frequently searched physical formats (items) and resource types.

A more complete list of publication types:

Table 1

Items owned by NLM - identifies items owned by the National Library of Medicine. For specific holdings, view the LocatorPlus record by using the link in the NLM ID or, on the Expanded Display, the NLM Holdings in LocatorPlus icon. The link opens a new window to display the record. Close the LocatorPlus window to return to the NLM Catalog results.

This feature will limit your search to full text documents.

Use the "From" and "To" boxes to specify a range of dates. For a single year, enter the year in both boxes. If no date is entered in the "To" box, the NLM Catalog searches the date in the "From" box through the Year 3000. If no date is entered in the "From" box, the NLM Catalog searches all dates preceding the one in the "To" box, starting with year 1.

The most common material types are listed in the drop-down menu. For a material type not on the list, enter it in the query box, qualified by the search field name Item Type [item] and Resource Type [res type].

You can search any field within an NLM Catalog record.

Preview
Displays the number of results for a search of the term(s) in the query box or of a term qualified by field:

• Select a field from the All Fields pull-down menu.
• Enter search term in the adjacent box.
• Click on Preview;     or
• Add the term to the query box by selecting a Boolean operator (AND, OR, or NOT) and start the search.
• Click on the result number to display the NLM Catalog records.

Index
Allows you to build a search, selecting from a list of terms within a search field:

• Select a field from the All Fields pull-down menu.
• Enter a term in the adjacent box; click Index for an alphabetic list of terms for the selected field.
• Select one or more terms from the list (multiple terms are ORed).
• Click AND to add the term(s) to the query box.
• When you have completed selecting terms from field(s),
  click on Preview to see the number of results or
  click on Go to see the NLM Catalog records.

Displays the search strategies and results of your searches.

• To view the results of a search, click on the result number.
• Use the pound sign (#) before the search number(s) to build on a search and to combine searches.

Examples:
#3 AND laser therapy
#5 AND #7

• Search result numbers may not be continuous. Some numbers are assigned to intermediate processes, e.g., displaying a record in another format.

This feature stores selected items from one or more searches. (To store items see "Send To".)

• Stored items can be sorted, displayed, printed, e-mailed, and saved to file.
• After 8 hours of inactivity, the contents of the clipboard will be deleted.

• Displays your search as it was translated by the NLM Catalog.
• Allows you to save a search query.
• Allows you to edit and resubmit a search query.
• May display error messages or notes.

Display

Display Order:
Records in the NLM Catalog are displayed in reverse publication date order, latest to earliest, except the most recent week's additions which appear at the top. Records that do not contain a date of publication sort at the bottom. See FAQ: Search Results Display . There are five display formats available in the NLM Catalog:

• Summary
• Brief
• Expanded
• Full
• XML
• Related Records in Catalog

For the fields displayed in the first five types see:

Table 2

Related records in the catalog:

Click the Related Records in Catalog link on the right side of a citation.

The Related Records link will retrieve a pre-calculated set of NLM Catalog citations that are closely related to the selected record. The related records will be displayed in ranked order from most to least relevant, with the “linked from” citation displayed first.

More information about Related Records:

• Each record in the NLM Catalog includes a link that retrieves a pre-calculated set of citations that are closely related to the selected article. NLM Catalog creates this set by comparing words from the title and MeSH terms using a word-weighted algorithm.
• If you select Related Articles from the Display menu without selecting specific citations, NLM Catalog will retrieve the related articles for the citations displayed on the page.
• Limits are NOT in effect when you use a Related Records link. Your initial search may have contained Limits, but after clicking the Related Records link there is no yellow bar displaying the Limits in effect.
• You can, however, refine the list of Related Records using NLM Catalog’s History feature. In History, you will see that the Related Articles retrieval is represented as " Related Records in Catalog for NLM Catalog (Select [NLM Catalog Unique Identifier Number])." Use this Search number in a search. (Keep in mind that the list you get with a Related Records link is displayed in ranked order from most to least relevant. Refining the list removes the ranked order and may remove citations that are most relevant.).

Sort

• Select a sort field from the Sort pull-down menu (NLM ID, Author, or Title)
• Click on Display
• Author and Title displays are sorted A to Z:
      Author sort, secondary sort is Title.
      Title sort, secondary sort is Author.

Send To

Provides ways to process search results through several options (Text, File, Clipboard, E-mail):

• Display selected or all search results as plain Text
• Save selected or all search results to a text File.
• Store search results on the Clipboard
• E-mail search resultsSelect E-mail from pull-down menu and click on Send to.
  Select Format and display (HTML or text) for the items.
  Select Sort.
  Select number of items to be sent.
  Enter e-mail address.
  Optionally, enter text (e.g., a message) in the 'Additional text' box.
  Click on Mail.

Note: Please see the Uniform Requirements for Manuscripts Submitted to Biomedical Journals and provided examples for information on standard citation formats used in biomedical journals.

Print - several print options available:

• Use the Print function of your Web browser to print the information on the Web page.
• Select 'Text' on the Send to pull-down menu and click on Send to. Use the Print function of your Web browser to print the text.Note: Use the Show pull-down menu to change the number of items displayed on a page.

Links (located to the right of each result)

• LocatorPlus: a link to the individual record in NLM LocatorPlus. Use your browser's Back button to return to the NLM Catalog results.

What is a "cookie"?
A "cookie" is information sent by a Web site server (e.g., NLM Catalog) to your computer. In the case of the NLM Catalog, it is information about your interactions that may be needed later to perform a function. Cookies allow the NLM Catalog to provide more interactive features such as Preview/Index, Clipboard, History, and My NCBI. Cookies placed by NLM Catalog are removed from your computer after a set time period.

How can I tell if my system accepts cookies?
Cookie-dependent features of the NLM Catalog include Preview/Index, History, Clipboard, and My NCBI. To use these features, your system must be able to accept cookies. If you still have problems using cookie-dependent features of the NLM Catalog even after enabling cookies, possible reasons may include:

• Cookies are blocked by your provider or institution. Check with your Internet provider and/or the system administrator at your institution to see if cookies can be accepted. Even if you have them enabled in your Web browser, if they are blocked by your provider or institution (e.g., by a firewall, proxy server, etc.), cookie-dependent features of the NLM Catalog won't work.
• Your computer's date and time settings are incorrect. Check your computer's time settings to ensure that they are correct.

Enabling Cookies
Given the number of possible combinations of computer platforms, operating systems, and Web browser versions, we are unable to provide instructions for enabling cookies on your computer. Consult your browser's Help for information on enabling cookies.

See the My NCBI for information about setting up a My NCBI account.

The NLM Catalog offers two filter options through My NCBI

• English
• Internet (Material Type)

Used to specify the publications or databases in which a title has been indexed and/or abstracted, and the status of the indexing if known.

Use "Preview/Index" to identify searchable values for the indexing publications or databases. These values include but are not limited to:

• Abridged Index Medicus
• Hospital and Health Administration Index
• Hospital Literature Index
• Index Medicus
• Index to Audiovisual Serials in the Health Sciences
• Index to Dental Literature
• International Nursing Index
• MEDLINE
• NLM Gateway meeting abstracts
• OLDMEDLINE
• PubMed

The searchable values for indexing status are:

• Ceased-publication
• Continued-by-another-indexed-title
• Currently-indexed
• Currently-indexed-Title-changed
• Date-range-of-indexed-citations-unspecified
• Deselected

Includes all searchable NLM Catalog fields.

The format to search for an author is: last name followed by a space and up to the first two initials followed by a space and a suffix abbreviation, if applicable. Do not use punctuation. Initials and suffixes may be removed when searching. The NLM Catalog automatically truncates on an author's name to account for varying initials. To turn off the automatic truncation, enclose the author's name in double quotes and qualify with [au] in brackets.

Identifies the corporate or conference name associated with an item. Corporate or conference names display exactly as they appear in the item. Use Preview/Index to build a search, to verify the form of name and/or spelling.

You can view the available filters by using the Preview/Index feature:

• Click on Preview/index on the action bar
• Under the "Add Term(s) to Query or View Index:" section, select "Filter" from the pull down menu
• Click the "Index" button
• The system will display the available filters, in alphabetical order, and, in parentheses, the number of items associated with that filter

The complete name of the author. The format is last name then a space and the full first name, a space and middle initial, if applicable.

This field contains data related to the format of the material. Contains one of the following values:

• Book
• Book Chapter
• Collection manuscript
• Collection print
• Electronic Resource
• Electronic Serial
• Kit
• Manuscript
• Map
• Mixed Material
• Nonmusical Recording
• Serial
• Still Image
• Three Dimensional Object
• Visual Material.

Includes the journal title abbreviation, full journal title, or ISSN number. If a journal title contains special characters, e.g., parentheses, brackets, enter the title without these characters.

You can also search for journals using the title abbreviation [ta] tag in the NLM Catalog.

The complete list of languages used is based on the official list of languages provided in the MARC Code List of Languages, a standard maintained by the U.S. Library of Congress.

To see the list of available languages, use the Preview/Index feature:

Click on Preview/index on the action bar

Under the "Add Term(s) to Query or View Index:" section, select "language" from the pull down menu

Click the "Index" button

The system will display the available languages, in alphabetical order, and, in parentheses, the number of items associated with that language

A MeSH term that is one of the main topics discussed in an item denoted by an asterisk on the MeSH term or MeSH/Subheading combination.

MeSH Subheadings are used with MeSH terms to help describe more completely a particular aspect of a subject. For example, the drug therapy of asthma is displayed as asthma/drug therapy. The MeSH Subheading field allows users to "free float." MeSH Subheadings automatically include the more specific Subheading terms under the term in a search. To turn off this automatic feature, use the search syntax [sh:noexp]. In addition, you can enter the MEDLINE two letter MeSH Subheading abbreviations rather than spelling out the Subheading.

Notes on MeSH Terms and Major MeSH Topic search fields:

• To search the term only as a MeSH term, qualify it using the search field tags, e.g., [mh] for MeSH Terms or [majr] for MeSH Major Topic. A qualified term is checked against the MeSH Translation table and mapped to the appropriate MeSH term. Some concepts may map to two or more MeSH terms. To turn off this mapping, enclose the MeSH term in double quotes and qualify with [mh], e.g., "cold" [mh].
• MeSH terms are arranged hierarchically by subject categories with more specific terms arranged beneath broader terms. MeSH terms in the NLM Catalog automatically include the more specific MeSH terms in a search.
• To turn off the automatic inclusion of the more specific terms, use the syntax [field:noexp], e.g., hypertension [mh:noexp], or hypertension [majr:noexp], or hypertension/therapy [mh:noexp]. The latter example turns off the more specific terms in both parts, searching for only the one Subheading therapy attached directly to only the one MeSH term hypertension.
• If parentheses are embedded in a MeSH term, replace the parentheses with a space and qualify with [mh].

• MeSH terms can be selected for searching in the “Preview/Index”. "_Preview/Index" Preview/Index.

The alpha-numeric identifier for the item that was assigned by NLM's integrated library system LocatorPlus.

Includes: general note, NLM catalog record owner, abstract, contents note, and other abstract.

Includes: ISBN, government document classification number, LCCN, other id, and report number.

Includes: broad journal heading and other subject name.

Use this search field tag to limit retrieval to where the name is the subject of the article. Search using the full name; last name comma space and the first name.

Use this search field tag to limit retrieval to records where the name is the subject of the title/material. Search names following the Author field format.

Indicates the country of publication of the item. Geographic regions are not directly searchable. In order to retrieve records for all countries in a region (e.g., North America) it is necessary to OR together the countries of interest.

Includes the statuses of a serial: open, closed, or unknown.

Describes the type of material the item represents; see the full list of publication types below.

List of publication types.

The year that the item was published. To enter a year range, insert a colon (:) between each year.

Contains the publisher.

This field contains one or more of the following values:

Related items with an overall title for the group; they may be numbered.

Words and numbers included in the title of an item. Do not use punctuation.

The Uniform Resource Locator or the Web address of a particular item. To search for URLs, the item must start with http:// and be enclosed in quotes. Also the URL must be the exact address of the item.

If you need more assistance, please select "Write to the Help Desk" on the bottom of each NLM Catalog page.

You may also contact NLM Customer Service at: http://www.nlm.nih.gov/contacts/custserv-email.html.
(888) 346-3656
(888) FIND-NLM