I recommend this book. It not only exclusively deals with DPN it also has line, by freaking line, with stitch count, the entire heel turn process.
http://www.amazon.com/Knit-Socks-Classic-Patterns-Cozy/dp/1603425497/ref=sr_1_1?ie=UTF8&qid=1451964169&sr=8-1&keywords=Knit+socks+book