A few years ago I visited the Olympia in Philadelphia and shortly after picked up some covers at auction. This cover does not have the Olympia cancel but it looks like the censor wrote Murmansk across the cover. I do not believe it had a cancel as the tear on the right is not large enough. The date is 12 Sep 1918. The Olympia was active during the White Army invasion and shelled Riga during the confusion.

Pochta