This gets complicated very quickly. Peter Hirtle created and maintains a useful resource for assessing when specific materials enter the public domain. You can access the Copyright Term table on the Cornell University Library Page.
You can contact Musselman Library's Copyright Committee at firstname.lastname@example.org.
The committee will offer a recommendation based on your situation, but the committee does not provide legal advice or serve as a substitute for consultation with competent legal counsel on matters regarding compliance with copyright law.