The most famous books about Soviet aggression against Finland in 1939-1940 I'm recommending for you, my friends:

1. Born a soldier. The Times and Life of Larry a Throne. By J. Michel Cleverly.
25 euros.

2. Finland at War 1939-45. By Philip Jowett and Brent Snodgrass.
18 euros.

3. Frozen Hell. By William Trotter.
17 euros.

4. White Death. By Robert Edwards.
17 euros.

5. The Winter War. By Eloise Engle and Lauri Paananen.
22 euros.

6. The Winter War. William Trotter.
16 euros.

7. The Winter War. By Robert Edwards.
32 euros.

And you may also buy another books (in Finnish) on that theme in Academic Bookstore in Helsinki (Akateminen Kirjakauppa), situated on the corner of Keskuskatu and pohj. Esplanadi, near Schwedish theatre.