I’ve tried to locate old encyclopedias from the early 1900’s, just to see what they have changed its eye opening, and yes It’s expensive for a complete set. Sad during the 1990’s people were throwing history books and encyclopedias away, thrift stores would not accept them any more. Tells you a lot about our society, that we throw our history out (books) in the trash. I rescued several books of history from trash heaps, I complete sets of encyclopedias refer to them as much as I can.