public domain, see below
Crop of an unnumbered page of the 1948 Pitt student yearbook, the Owl. This work was originally published before 1964 had to have the copyright renewed sometime in the 28th year. If the copyright was not renewed the work is in the public domain. It is best to search 6 months before and after the required year. Some periodicals are published the month before the cover date and some registrations may be delayed for a few months.
Originally this issue of The Owl student yearbook was seemingly published without a copyright notice, but if it was published with a copyright notice it would have had to be renewed in 1975. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. [1]
The search of the Renewals for Books and Periodicals for 1974, 1975, 1976, and 1977 show no renewal entries for The Owl by the editor Walter L. Thompson, III, the business manager Mavis Loeffler, the Owl itself, or the University of Pittsburgh.
The Owl was never copyrighted or the copyright of the yearbook was not renewed and therefore it is in the public domain according to either criteria.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.