Here are a couple of sites that might be helpful in your research:
https://wiki.familysearch.org/en/Portal:Russia (It has a German link which lists resources at the LDS library.)
http://feefhs.org (An umbrella organization that has some good links. It provides a forum focused on a single country or group of people to exchange information.)
And, did you know that AHSGR is on Facebook? Check it out. Who knows, maybe you can connect with someone there that might help you in your research.