Cita APA (7a ed.)

Hay, P., Phillips, D., & Sheerin, S. (1990). Signature -: Workbook. [s.n].

Cita Chicago Style (17a ed.)

Hay, Pat, Diane Phillips, y Susan Sheerin. Signature -: Workbook. NelSon, U.K: [s.n], 1990.

Cita MLA (9a ed.)

Hay, Pat, et al. Signature -: Workbook. [s.n], 1990.