Reference areas were (and some still are) situated near tremendous libraries of reference books (like Encyclopedias, telephone directories, almanacs, etc.) and those were usually sufficient to address many of the types of questions the author lists. If you ever go to a rare book library, like the Lilly at Indiana University, the Beinecke at Yale, etc. (which you can visit for free!), the old school rare books librarians are still adept at using their reference books to answer questions pertaining to their trade. Those reference books are also highly sought after by said librarians and other book collectors.