Viking Patterns for Knitting is one of those books that seems have a narrow focus, but turns out to have something for just about anyone.
There are 14 projects in this book, but the techniques and charts are the stars of the show.
Lavold goes back and gathers ideas for cabled motifs from Viking ornamental pieces, like buckles, tombstones and shield plates. The designs are then executed into sixty different knitting motifs.
If you do pick up this book, be sure to check out the errata page.

