Books are everywhere, collectors, ebay, amazon, garage sales, libraries.
Just because it isn’t convenient, doesn’t mean it doesn’t exist.
The Internet is convenient and google/Wikipedia is easy to use so those are the areas that can be easily manipulated.
I will amend my comment;
“”””””’Nobody can log into a 1950’s history book and change the information.””””””””””
Good luck finding one......in a school or public library.