The Internet Archive is a nonprofit digital library. This website is not about elevators, but there are some elevator-related parts of this website.
Historic elevator catalogs & books
This website has digital scans of historic catalogs, including scans of some historic elevator catalogs, and books.
The Wayback Machine is a part of the website with a huge amount of archived versions of web pages, dating from late 1996-present. Using the Wayback Machine, you can view archived versions of elevator company websites.