Cita APA (7a ed.)

Wilson R. Robin. (2003). Four Colours Suffice. How the Map Problem was Solved. London, Penguin Books, 2003.

Cita Chicago Style (17a ed.)

Wilson R. Robin. Four Colours Suffice. How the Map Problem Was Solved. London, Penguin Books, 2003, 2003.

Cita MLA (9a ed.)

Wilson R. Robin. Four Colours Suffice. How the Map Problem Was Solved. London, Penguin Books, 2003, 2003.