It’s simply not true that there “aren’t really that many definitions of OOP”, much less that the guide you’ve linked is “comprehensive” when it is specifically about Java.

This is a good, brief post about the different conflicting definitions: https://paulgraham.com/reesoo.html

This is a much more comprehensive but also less focused overview, with many links, from a site that is effectively both a wiki and a forum: https://wiki.c2.com/?ReesOnObjectOrientedFeatures