Gray, E., & O'Sullivan, N. Practice Tests for the PET 1 Preliminary English Test: Class CDs. Express Publishing.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रGray, Elisabeth, और Neil O'Sullivan. Practice Tests for the PET 1 Preliminary English Test: Class CDs. Newbury: Express Publishing.
एमएलए (8वां संस्करण) प्रशस्ति पत्रGray, Elisabeth, और Neil O'Sullivan. Practice Tests for the PET 1 Preliminary English Test: Class CDs. Express Publishing.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.