To be honest I don't have a book that I am using.
I am comparing everything to my Springfield Mil Spec.
I have used www.sightM1911.com
for a whole lot of my information. I have also gone into the archives here at the TFF (that is a treasure trove indeed).
I have completely taken apart my 1911 three times to familiarize myself with all the internal parts.
Essentialy I have been reading everything I can get my hands on.
When I have been reading the information I will have my Mil-Spec taken apart going back and forth from the written stuff to the parts themselves to learn what does what.