Obviously there are redbooks from over the years. And via the IBM website there are the different sets of official documentation sets.
And, depending on your education budget, the IBM course: AU54/AU054 (same course, slightly different codes) are highly recommended.
Personally, I do not know of third-party/independent authors writing on HACMP - but that is just me.
Redbooks: http://www.redbooks.ibm.com and search for HACMP.
The official (whitebooks) are in the vgBookmarks, or are suppossed to be!
