When I started collecting photos, I started, at the same time, documenting and learning everything about photography in order to be well informed and teached.
The first book from which I got a lot of useful information was "150 años de fotografía en España" by Publio López Mondéjar.
After this book, I had few more where I could get some data but the great book I discovered was "On photography" by Susan Sontag.
The book consists on several short essays that explains what or why of everything about photography. It explains the reasons, its future, the difference from other arts and puts it on its place of culture.
Susan Sontag, who died in 2004, was photographer Annie Leibowitz couple.
His book is full of words, ideas and images. Reading this book reinforces and complements collectors view on photography which is what the collector is looking for in order to choose the best pictures.
"Photographs depict realities that already exist, though only the camera can disclose them. And they depict an individual temperement, discovering itself through the camera's the cropping of reality."
It also tells us that:
The name that Fox Talbot chose when he patented the photography was Kalotype from "kalos", beautiful.