title: The PNAS way back then.
authors.affiliation: Department of Mathematics, University of Chicago, Chicago, IL 60637, USA.
authors.forename: S
authors.initials: S
authors.lastname: Mac Lane
mesh_terms: D049673:History, 20th Century; D009307:National Academy of Sciences, U.S.; D010506:Periodicals as Topic / Q000266:history*; D011643:Publishing; D014481:United States