The original reference, in days before the internet and Wiki-whatever, was a good set of encyclopedias. They were a luxury item, something that said you'd made it into the intellectual set. You were the sort of person who needed to look up the salient facts about gutta percha or the mean income of the average citizen of Lesotho. Yes, the world was at your fingers, as soon as you could figure out where Junior put the D volume.
My mother forever was picking up stray encyclopedias at garage sales and thrift shops. We had about three incomplete sets and all of them seemed to be missing the one book you needed when doing a report for school. All the more excuse to put off homework until later!