As suggested the Peterson's Guides tend to be very useful. I personally don't have one specific to Raptors, but have been considering getting one. I had on my list of those to consider the one you said that you have. I take it from your comments that it fails to live up to the promise of "hawks from every angle"
There are Peterson Field Guides to a number of specific birds. The one on Raptors is written by Clark and Wheeler.
There are many Guides available. You might want to take a look at the following Website where reviews of many bird books are given.
The address is http://www.birderslibrary.com. Once there you can do a Search for the particular subject or bird you are interested in.
p.s. I hope that a previous person who Posted looking for suggestions of Guides is still checking in! They may benefit also from the Website.
http://whatbird.com/forums/photos/birdman/
