I purchased a few more resources at the Fort Collins Conventions this year that I am happy to share. I can bring them out for you to look at when we meet next if you let me know you're interested.
German Migration to the Russian Volga (1764- 1767); Brent Alan Mai
The Volga Germans in Old Russia and in Western North America: Their Changing World View; Timothy Kloberdanz
The Story of the Volga Germans; George J. Walters
The Christmas Keeping Germans; Neita Oviatt Friend
Letters from Hell; Samuel D. Sinner