This English-language site contains a bibliography of archival guides. It also includes descriptions of the major Russian archives.
Official site of the Federal Archive Agency. Russian-language website with the most up-to-date information about archives, museums, libraries and their collections. Also contains lots of information about various guides to archives.
Use the Archives Hub to find unique sources for your research, both physical and digital. Search across descriptions of archives, held at over 350 institutions across the UK.