Okca?

A friend of the family brought over a loose group of world-wide stamps. Although I concentrate solely on US postage, I was able to identity by country all but five related stamps. These five have me stumped. I apologize for not being able to have these available on scans, but my scanner is hard broke so I'll only be able to describe them. They are all imperf on very thin paper with no gum and all appear unused. The only readable Romanized letters on all five is the word "OKCA". It appears in block letters on two of them and a very fancy monogram-type script on the others. There are in five different colors - yellow, blue, orange, green, and maroon. The yellow one has a value on it of "15". The blue one has a "10", and the maroon one "5". Military arms appear on two of the items. The blue one has two parallel swords and the green one has two crossed axes behind a circular shield. The quality of printing on all seems very amateurish with other possible values and words completely unreadable. They appear to be pre-World War II, but this is just a swag. Any ideas on what country could be from?

Never mind. Searched in archives and found what I needed. Army of the North in Northwest Russia. Now why didn't I look there first!

Lesson Learned, Grasshopper

Here is the link:

https://goscf.com/t/18358#18358