The groups relating to e-books to my knowledge at
this time:
NOTE: The *.mathmad and *.technical groups were formed incorrectly as a knee-jerk response to a problem with flooders of those types of materials, (these are known as "rogue" groups) and it's very possible that your posts won't be propagated widely if you post there. However, against all reason, they are slowly being added to more and more news servers, so it may simply be a matter of time until they are used as much as the other e-book groups.