Tvåändsstickat by Dandanell and Danielsson.
This is, in my opinion, the best book about twined knitting available. It deals with both the technique and the history of twined knitting. It also contains basic patterns and lots of interesting pictures.
The book was reprinted and revised in 2011 by Dalarnas Museum, but only in Swedish. I contacted the Museum suggesting an English translation but did not succeed in convincing them.
Now there is a petition for publication of "Tvåändsstickat" in English at The Dutch Knitters homepage. If you are interested in making an English version available do follow this LINK for more information and sign the petition.