Problem Time: 3/31/2016 edition

First a mate in two.

Lev Sokolov 

Shakhmaty v SSSR, 1937 

I believe you should be able to move the pieces in the board above. (Correction: You can move the pieces, but only if you make the correct move.)

Next an endgame study. White to play and win.

E. Pogosiants, 1981

Unfortunately that's all the information I've got on the Pogosiants study. I came across both of these playing against ICC's ProblemBot, though I've seen the Pogosiants study on Chess.com as well.

Finally, an oddity.

Ten Kings, Ten Mates

White mates all ten kings in one move

Gustav Reichhelm, Bretanos Chess Monthly, 1882

Answer in the comments.