Thanks backat'cha for sharing your research. Great stuff well worth a rainy day in the basement stacks of a University library!
Steigmann is a player you should probably look into. I've never been able to find out much about his personal story, but he researched and wrote extensively, much of it for German emulsion factories. His earliest writing I've seen is 1924. Fortunately, his favorite references are his own earlier publications -- makes him easy to backtrack. Unfortunately, he wrote much of the earliest stuff in German journals. He seems like he was rather full of himself, but it's possible that was justified. Anyway, interesting guy, and under-appreciated, I think, in photographic technology history. I'm always on the lookout for more info on him.
He presented a couple of papers at the 1959 Colloquium of Scientific Photography. "Peptized Silver Bromoiodide Emulsions of Negative Speed" speaks extensively of gold sensitization, but both papers have a number of citations (many by Himself) that you might have use for. Most are from the late 20s and early 30s. Scientific Photography--Proceedings of the International Colloquium Held at Leige 1959, Edited by H. Sauvenier, Pergamon Press, 1962.