The New Breed of Version Control Systems
http://www.onlamp.com/pub/a/onlamp/2004/01/29/scm_overview.html

Fish, Shlomi
O'Reilly and Associates
2004

Abstract:

CVS, part of the glue that holds open source development together, is showing its age. Many competitors have emerged recently, fixing misfeatures and adding new ideas. Shlomi Fish explores several current open source version control systems that may be better than CVS for your needs.