Currently I am reading a textbook (in financial mathematics), and the bibliography is just huge. Pages upon pages of books and articles and whatnot. I'm talking hundreds of sources.
Did the author really read all of those things during the course of writing the book? Is that normal?
Or is it just something they think will be useful for students, i.e. a source they may know as popular in the field but haven't read themselves? For example, somebody in mathematics might now of books by Rudin and what topics they contain, without ever actually have read themselves, so they could use that as a source without having read it, i.e like this:
for further information about functional analysis, see (Rudin, 2003) .