Perrin gave a 1956 discussion:
http://image.eastmanhouse.org/files/GEH_1956_05_06.pdf

He did not mention the type of developer, the effect of which was mentioned by Adams:
http://image.eastmanhouse.org/files/GEH_1959_08_01.pdf

Presumeably there must have been some later proprietary work, I have not looked through the references in Dr Henry's book.