Atom References
Lotus Connections References
These are some references that I have found very useful that should help you as well. These are rather technical:
Video Introduction to Atom - Joe Gregorio
Atom API Quick Reference - bitworking.org
Atom Publishing Protocol - bitworking.org - spec
Extending Atom Using XML - bitworking.org
Atom Syndication Format (Feeds) - atompub.org - spec
RSS/Atom Feed Validator - feedvalidator.org
Valid MIME Types - w3schools.com
HTTP Response Codes - w3.org
Basic Authentication - wikipedia.org
Lotus Connections References
Here is some of the publically available Lotus Connections Documentation. You may find these useful as well: