There are quite a few old Russian papers and books I've been trying to track down for a few months without success. (I have some listed here.) Many old Russian journals and books are in US libraries, and I think I'm aware of all or nearly all of the resources my library has available to me. If the journal is not available in the local library or online, I'll look on WorldCat, and use my library's interlibrary loan service if I can find an entry on WorldCat. Basically, if it exists on WorldCat, the interlibrary loan service is likely to obtain the paper, and if not, I'm usually out of luck. Overall my success rate is probably only about 50%.
Herein lies the problem. Very few Russian libraries participate in WorldCat, and in my experience libraries outside of the US are less likely to provide scans. Basically everything I have been able to locate this way existed in the US, and there are many Russian journals which never seem to have made the trip to the US. Or if they did make the trip, they exist only in the Library of Congress, which requires you to visit in person. (Not such a huge issue for me, as I have family in the DC area, but this could be prohibitive for others.)
Are there any resources in particular for Russian papers that I should be aware of?
The previous question titled "What do you do when you find yourselves with an unreadable/inaccessible paper?" is related to this, but I'm aware of everything mentioned there and/or what is mentioned there is not applicable, and am looking for something more specific to locating Russian papers in the US.
(I'm looking for engineering and physics papers primarily for experimental data and models to use in my own research. In general, these papers are quite old such that the authors are inaccessible, though in most cases the journals are still active.)