Cita APA (7a ed.)

Kerr, P., & Jones, C. (2012). Straightforward: Upper intermediate Workbook : with answer key (2nd ed.). MacMillan.

Cita Chicago Style (17a ed.)

Kerr, Philip, y Ceri Jones. Straightforward: Upper Intermediate Workbook : With Answer Key. 2nd ed. Oxford: MacMillan, 2012.

Cita MLA (9a ed.)

Kerr, Philip, y Ceri Jones. Straightforward: Upper Intermediate Workbook : With Answer Key. 2nd ed. MacMillan, 2012.