There's surprisingly not that much on the net that I'm finding. I learned about it from a traveling exhibit that came to a localish museum to me, but it's all extremely recent (in comparison to most paleontological discoveries) mostly really becoming an overwhelming body of evidence in the last 30 years or so, but the earliest discoveries date to the 70s and 80s.

Looks like PBS Nova did a documentary called "Arctic Dinosaurs" and I linked a BBC article in another comment that gives a good overview as well.