Citing an appendix written by the book author: Citing a single appendix: Penguins are one of the rare examples of monogamous arctic birds (Lee, 2016, appendix). Citing multiple appendices: Lee describes several notable interactions between researchers and penguins (appendix A); he also includes the translated research notes of French scientist Jacques Dupont (appendix B). References: Lee, S. (2016). Flying Between The Poles: The Evolution of Birds in the Arctic. New York, NY: Avem Publications. Citing an appendix written by a separate author: In her appendix to Catherine Johnson’s Habits of North American Birds, Leah Stone details the complicated diet of the American sparrow. References: Stone, L. (2014). Appendix: The Diet of the American Sparrow. In C. Johnson (Ed.), Habits of North American Birds (pp. 340-345). New York, NY: Avem Publications.