APA (7e ed.) Bronvermelding

Gray, E., & O'Sullivan, N. Practice Tests for the PET 1 Preliminary English Test: Class CDs. Express Publishing.

Chicago (17e ed.) Bronvermelding

Gray, Elisabeth, en Neil O'Sullivan. Practice Tests for the PET 1 Preliminary English Test: Class CDs. Newbury: Express Publishing.

MLA (8e ed.) Bronvermelding

Gray, Elisabeth, en Neil O'Sullivan. Practice Tests for the PET 1 Preliminary English Test: Class CDs. Express Publishing.