Cita APA (7th ed.)

Lloyd M. Mark, Day J. Jeremy, & Ur P. Penny. (2011). Active Grammar: Level 3 with answers. Cambridge, Cambridge University Press, 2011.

Cita Chicago (17th ed.)

Lloyd M. Mark, Day J. Jeremy, i Ur P. Penny. Active Grammar: Level 3 with Answers. Cambridge, Cambridge University Press, 2011, 2011.

Cita MLA (9th ed.)

Lloyd M. Mark, et al. Active Grammar: Level 3 with Answers. Cambridge, Cambridge University Press, 2011, 2011.