Gray, E., & O'Sullivan, N. Practice Tests for the PET 1 Preliminary English Test: Class CDs. Express Publishing.
Cita Chicago (17th ed.)Gray, Elisabeth, i Neil O'Sullivan. Practice Tests for the PET 1 Preliminary English Test: Class CDs. Newbury: Express Publishing.
Cita MLA (8th ed.)Gray, Elisabeth, i Neil O'Sullivan. Practice Tests for the PET 1 Preliminary English Test: Class CDs. Express Publishing.
Atenció: Aquestes cites poden no estar 100% correctes.