Library of Congress Online Catalog: Help Pages

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  SEARCHING:
  Basic Searching
  - Title
  - Author/Creator Browse
  - Subject Browse
  - Keyword
  - Command Keyword
  - Call No. Browse (LC)
  - Call No. Browse (Other)
  - LCCN-ISBN-ISSN
  - Series/Uniform Title
  - Author/Creator by Title
  Guided Searching


  Limiting Searches
  Search History
  Boolean Searching

  INDEX CODES:
  for Guided Searches
  for Command Keyword

  SEARCH RESULTS:
  Brief Record
  Subjects/Content
  Full Record
  MARC Tags


  Headings List
  Titles List
  Titles List (Keyword)
  References/Scope Notes
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  OTHER TOPICS:
  Headings List Types
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  Database Selection
  Icons, Buttons & Tabs
  Session Time-Outs

Basic Search - Keyword
finds words or phrases located anywhere in the catalog record.

Basic Search - Keyword

Use Keyword searches when it is not clear where words or phrases relating to the material for which you are searching are likely to fall in catalog records, when terms may appear in different places in different records, or when there are no results using other types of searches.

Because the keyword search is set up to look for any of the words entered and because of the very large size of the Library of Congress database, keyword search results can be very imprecise. The records display according to the system's evaluation of their relevance, but it is strongly recommended that special punctuation symbols be used to ensure more precise searching.

NOTE:
Search limits are available.
Boolean operators (AND, OR, NOT) are not available.

Basic Search Examples:

Search string . . . Retrieves catalog records containing . . .
"history of analog comput?" history of analog: computer, computers, computing, computation, etc.
"eating and drinking" the exact phrase; would be different from the search "eating drinking" or "eating & drinking"
+canadian !bacon the word "canadian" eliminating any that also include the word "bacon"
"civil war" !fiction the exact phrase "civil war" eliminating any that also contains the word "fiction"

Search Tips:

  • Enter words or phrases in any order.

  • All words will be searched including "and", "or", "not", "the", "a", "la", "das", etc.

  • Use quotation marks (" ") to retrieve exact phrases (e.g., "tax reform")

  • Use ? at the end of a search word for truncation (e.g., ecumen? will retrieve ecumenical, ecumenism, etc.).

  • Use special punctuation to refine the search: + (in front of word that must appear), ! (in front of words that must not appear), and * (in front of words to raise relevance).

  • Search results are ranked using a relevancy algorithm. To improve the relevancy of the results it is usually better to include more words or phrases in the search, in addition to using the suggested punctuation tools.

About Relevancy Ranking:

Keyword search results are displayed as a Keyword Titles List in ranked order using a special relevancy algorithm. Although relatively new to library online catalogs, relevancy ranking is used by many Web search engines (e.g., AltaVista, Lycos, etc.) However, each formula for determining relevance is a little different. Here is some information on the ranking factors used in the Library of Congress Online Catalog:

  • Uniqueness of search terms within the database
  • Proximity of search terms to each other within the catalog record
  • Number of times a search word is present in catalog record fields (e.g., subject heading field, author field, title field) in which the terms occur.
  • Use of * and + operators: the asterisk raises the relevance of a term; the plus sign requires the term to be present in the results.

Alternative Search Options:

If specific information is known (e.g., an author, title, subject term, etc.), it is better to use a Basic Search (other types) or Guided Search (offering guided structuring of Boolean and index-limited searches).

If a Keyword search retrieves too many catalog records (a common problem with Keyword searching), try using a combination Keyword and Subject search by following these steps:

  • Within the Keyword search box, type in words and/or phrases in any order.
  • Review the results list and identify a relevant catalog record.
  • Select the Subjects/Content tab to review the displayed subject headings.
  • Perform a new search using one of the relevant subject heading by selecting its hypertext link.

Use the browser's [Back] button to resume searching.

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November 17, 2005