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Volume 26(12);  December 15, 1940
Astronomy
Galactic and Extragalactic Studies: XI. Note on the Period-Frequency of Galactic Cepheids
Harlow Shapley
Proc Natl Acad Sci U S A. 1940 December 15; 26(12): 681–688.
PMCID: PMC1078253
Botany
The Absorption of Bicarbonate Ion by Barley Plants as Indicated by Studies with Radioactive Carbon
R. Overstreet, S. Ruben, and T. C. Broyer
Proc Natl Acad Sci U S A. 1940 December 15; 26(12): 688–695.
PMCID: PMC1078254
Mathematics
A Remark on General Fuchsian Groups
Guido Fubini
Proc Natl Acad Sci U S A. 1940 December 15; 26(12): 695–700.
PMCID: PMC1078255
The Distance in General Fuchsian Geometries
Guido Fubini
Proc Natl Acad Sci U S A. 1940 December 15; 26(12): 700–708.
PMCID: PMC1078256
Abstract Definite Boundary Value Problems
J. W. Calkin
Proc Natl Acad Sci U S A. 1940 December 15; 26(12): 708–712.
PMCID: PMC1078257
Unstable Minimal Surfaces of Higher Topological Types
Marston Morse and C. B. Tompkins
Proc Natl Acad Sci U S A. 1940 December 15; 26(12): 713–716.
PMCID: PMC1078258
Zoölogy and Anatomy
The Development of Melanophores from Embryonic Mouse Tissues Grown in the Coelom of Chick Embryos
Mary E. Rawles
Proc Natl Acad Sci U S A. 1940 December 15; 26(12): 673–680.
PMCID: PMC1078252
Journal Matter
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