Cita APA (7a ed.)

Hammond, N., & Webb, M. (2006). How to identify birds. HarperCollins.

Cita Chicago Style (17a ed.)

Hammond, Nicholas, y Michael Webb. How to Identify Birds. London: HarperCollins, 2006.

Cita MLA (9a ed.)

Hammond, Nicholas, y Michael Webb. How to Identify Birds. HarperCollins, 2006.