There isn't that many books in English unfortunately. I would probably suggest taking a look at Gordon Sander's The Hundred Day Winter War: Finland's Gallant Stand against the Soviet Army. It is rather unashamedly rooting for the Finns, but it's well-written and a good read.

Another book, less readable in my opinion and more focused on military moves, is William Trotter's Frozen Hell. There's also a book by Russian historian Bair Irincheev, War of the White Death: Finland against the Soviet Union, 1939-40. I haven't read it but Irincheev is probably the foremost Russian historian of the Winter War, and the stuff I've read from him is good.

The rest of the English-language books are old and dated, and I'd say start from these three first.