When I was growing up, my parents bought a set of Compton’s Encyclopedias that were proudly displayed in our living room. They were our source of information for projects in both elementary and secondary school.
Annually, a paid for year book arrived with updated information. It went on for more than a decade.
Our elementary school had two or three different sets of encyclopedias to search for information. The biggest set was the Britannica series that came in both a junior and senior version.