Thank you for the answer!
As I understand the footnote plugin allows you to add a reference to sources, similarly how wiki works. My request is a bit different - when you open a new topic in the Q&A forum, apart from the title, it will also ask you for the book name (maybe dropdown of supported books), the question number and the page number (if the question is not from a book, it’s possible to mark as “not from book”).
If there is no such plugin, maybe there is some plugin that added custom extra topic fields that I can take a look into their source code?