R4 IK
There is a 3 volumn set by Kapanji, I don't remember the name specifically but
they are broken down into vertebral motion, and axial motion. They are soft
covered and not that expensive, just call up any medical book store and asked
for Kapanji's text. They are pretty much the gold standard. Just a word of
caution, the way they are printed it looks like pretty simple reading, lots of
line illustrations but you will need to get a good working knowledge of the
anatomy terminology and the way they break the different 3 dimensional planes
down which is different than animation planes. They assume you have a good
knowledge of this already, if not pick up a good medical dictionary such as
Dorland's. Hope this helps Sam