Open Source Development with CVS by Karl Fogel, http://cvsbook.red-bean.com/
Available in paperback (2nd edition, July 2002) - ISBN: 1932111204
An excellent resource for learning the ConcurrentVersionsSystem, available on-line and on DeadTree. Not to be confused with TheCederqvist.
You might also want to check out "Essential CVS", recently published by O'Reilly. ISBN: 0596004591 . I found it to be pretty good.
CVS - Concurrent Versions System. Written in portuguese by Cristiano Caetano. Available at novateceditora.com.br/livros/cvs/. ISBN: 85-7522-051-9