Cita APA (7th ed.)

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

Cita Chicago (17th ed.)

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

Cita MLA (8th ed.)

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