The official Ubuntu book.

MLA

Hill, Benjamin Mako, Jono Bacon, and Ivan Krstic. The Official Ubuntu Book. 2nd ed. Upper Saddle River: Prentice Hall, 2007.

APA

Hill, B. Mako, Bacon, J., & Krstic, I. (2007). The official Ubuntu book. 2nd ed. Upper Saddle River: Prentice Hall.

Chicago

Hill, Benjamin Mako, Jono Bacon, and Ivan Krstic. The Official Ubuntu Book. 2nd ed. Upper Saddle River: Prentice Hall, 2007.