the back for a knit, and to the front for a purl, this results in two sheets of stockinette stitches, with the wrong (purl) sides facing each other. Switching colors ties the two sides together for a single, double-thick fabric. This method is often used for elaborate, two-color designs, as there are few constraints on how the colors may be used. The finished item from this method is reversible, each side holding the negative image of the other. References Baber, M'Lou (2008). Double Knitting: Reversible Two-Color Designs. Schoolhouse Press. . Hiatt, June Hemmons (1988). The Principles of Knitting. Simon and Schuster, pp. 233–247. . Post-Quinn, Alasdair (2011). Extreme Double-Knitting: New Adventures in Reversible Colorwork. Cooperative Press. . Royce, Beverly (1994). Notes on Double Knitting (expanded edition). Schoolhouse Press. . Stamper, Kory (2006). "Extreme Knitting: 2 socks in 1". Knitty.com. Knitting