There are are a couple of new books out or coming out that seem worth investigating.
The first is a book by Majorie Burns titled Perilous Realms: Celtic And Norse in Tolkien’s Middle-Earth. From a review in the Rutland Herald:
There’s a new book out on the “Lord of the Rings” and its accompanying volumes that says J. R. R. Tolkien’s writing is much more subtle and nuanced than most people have realized. Marjorie Burns, a professor in the Department of English at Portland State University, says Tolkien blended Norse and Celtic factors in a delicate, abstruse manner that makes the works as scholarly as they are entertaining.
The second looks to be a special collected edition called the Runes of Ragnan. From an announcement on the upcoming collected edition:
This Fall, Silent Devil will unleash the Viking epic Runes of Ragnan in a collected edition containing the complete four-issue mini-series. Written by Ty Gorton, drawn in high action detail by Josh Medors (G.I. Joe, In The Blood, FUSED!), with colors by Jay Fotos (Spawn: The Dark Ages, Vampirella, The Nail), the collected edition will include a 5-page prequel, an exclusive short story with visuals by Bud Cook, contest winning artwork, and a behind the scenes feature.
From a review of the original series:
Runes of Ragnan is a comic that delivers a great story that blends elements of fantasy and actual Viking lore. Gorton’s story quickly sucks you into the comic, and keeps your interest through every page. Most important, the first issue leaves you wanting more, and not completely sure where Gorton is going with his story.
The third is a new edition of the Dictionary of Northern Mythology by Rodolf Simek and Angela Hall.