The yearbook has no copyright markings on it. Also, there is no copyright registration either for the years 1948 and 1949. Therefore, it lapsed into public domain.
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 (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.
Uploaded a work by [https://dl.mospace.umsystem.edu/mu/islandora/object/mu%3A210082#page/414/mode/2up Ghio Studio] from [https://dl.mospace.umsystem.edu/mu/islandora/object/mu%3A210082#page/100/mode/2up Savitar '48] with UploadWizard