Cita APA (7a ed.)

Phillips, D., & Sheerin, S. (1990). Signature _: Teacher?s book. [s.n].

Cita Chicago Style (17a ed.)

Phillips, Diane, y Susan Sheerin. Signature _: Teacher?s Book. NelSon, U.K: [s.n], 1990.

Cita MLA (9a ed.)

Phillips, Diane, y Susan Sheerin. Signature _: Teacher?s Book. [s.n], 1990.