I want to run a Scandinavian/viking campaign. Other than Land of Linnorm Kings, People of the North, and Giants Revisited what books would you recommend. I am probably going mythic. I am open to third party, other rpgs and nongamming books.
Beowulf
Watch history channels "Vikings" for some inspiration.
Osprey makes many books on Vikings and norse cultures and methods of warfare.
as far as gamey stuff, I found all I really needed to do a Viking -ish game setting is in the CRB and a tiny bit from some of the ultimate books.
Many of the later introduced classes have a very hard time fitting into a Viking closed world feel campaign...but that's my take, anyway good luck.
I'd say look to Dark Horse Comics interpretation of Conan in general for the Golarion setting. Though "Volume I: The Frost Giant's Daughter" definitely stands out as an arc that would fit into the linnorm kingdoms.
Game of Thrones' chapters focusing on Jon and Sam and The Night's Watch are, I believe, a significant inspiration behind The Blackravens of Hagreach.
The Vikings (with Kirk Douglas) also features an entertaining if sometimes campy viking tale.
As for classes that "don't belong". Halgrim is considered highly cosmopolitan, and White Estrid is very open to embracing traditions and travellers from the south. Likewise, Freyr Darkwine needs every able soldier or spell caster he can get his hands on.