Cita APA (7a ed.)

Gray, E., & O'Sullivan, N. (2003). Practice Tests for the PET 1 Preliminary English Test: Student's Book. Express Publishing.

Cita Chicago Style (17a ed.)

Gray, Elisabeth, y Neil O'Sullivan. Practice Tests for the PET 1 Preliminary English Test: Student's Book. Newbury: Express Publishing, 2003.

Cita MLA (8a ed.)

Gray, Elisabeth, y Neil O'Sullivan. Practice Tests for the PET 1 Preliminary English Test: Student's Book. Express Publishing, 2003.