"Oswald's shirt appears to be Russian. "
Ralph Thomas is correct. Oswald's shirt, the one he wore in the doorway, on the bus as seen by Mary Bledsoe, and in the theater when he was arrested, the one found to have a bus transfer ticket in the shirt pocket, was one that Oswald acquired in Russia and brought back with him from Russia. It was not a standard American shirt with a stiff collar and a stiff placket. The material was soft, and it folded over, unlike American shirts do, and that's what gave it the look of a jacket.
American shirts don't do that. Note that none of your shirts do. Yet, in 2013, the Newseum tried to foist this (below) off as Oswald's shirt. Look how stiff that collar is! That shirt could never behave like Oswald's.
They have been lying about Oswald's shirt since Day 1. And that's to hide the fact that he was wearing it in the doorway.