The Project Gutenberg FAQ 2002

book itself is eligible, but introductions, indexes, footnotes,

glossaries, commentaries and other such extras may have been added by the modern publisher, so you should not include them except where you can prove that they are part of the reprinted material.

C.20. I have a text that I know was based on a pre-1923 book, but I don't have the title page. Can I submit it to ...