History of publication of von Neumann's characterization of orthogonally invariant matrix norms Von Neumann has a result (rather well-known in convex analysis circles) which states that every orthogonally invariant matrix norm (meaning $\| P M Q\| = \| M \|,$ for any orthogonal $P, Q$) is a symmetric gauge of the singular values. This is a very nice and very useful result, for which the reference is (see also bibtex below):
J. von Neumann, Some matrix inequalities and metrization of matric space.
Mitt. Forschungsinst. Math. Mech. Kujbyschew-Univ. Tomsk 1, 286-300 (1937).
The question is really one of history:

how did von Neumann (who was already in Princeton at the time) decide to publish in a Tomsk University proceedings?

Tomsk is very far from anywhere in Russia, and I am not aware of anything else that appeared there.
Bibtex reference:
@Misc{zbMATH02519847,
     Author = {J. {von Neumann}},
    Title = {{Some matrix inequalities and metrization of matric space.}},
    Year = {1937},
    Language = {English},
    HowPublished = {{Mitt. Forschungsinst. Math. Mech. Kujbyschew-Univ. Tomsk 1, 286-300 (1937).}},
    Zbl = {63.0037.03}
}

 A: Probably there is no way to know it for certain, but it's a safe bet that this  was related to Fritz Noether https://en.wikipedia.org/wiki/Fritz_Noether .  He was a brother of Emmy Noether  and also a mathematician (although not nearly as famous as his elder sister).  Apparently, 
he is best known for his work in   relativity   (Herglotz-Noether theorem).
As is well known, Emmy Noether moved to US after Nazi government  dismissed  Jews. Her brother, instead, moved to  USSR. (Which, in hindsight, was not a very good idea.)  He was appointed  there to a professorship at the University of Tomsk. (Look at his publications in 1935-1937
 http://www-history.mcs.st-and.ac.uk/Extras/Fritz_Noether_publications.html.) 
Of course, Von Neumann should have being  familiar with  Fritz Noether, so it is not a miracle if  he sent him a paper or two. 
Then there was  the Great Purge.   In 1937 (the same year the mentioned paper was published) Fritz Noether  was arrested at his home in Tomsk. He was shot in Orel on September 10, 1941, and his burial place is unknown.
