Gray, E., & O'Sullivan, N. (2003). Practice Tests for the PET 1 Preliminary English Test: Student's Book. Express Publishing.
Цитирование в стиле Чикаго (17-е изд.)Gray, Elisabeth, и Neil O'Sullivan. Practice Tests for the PET 1 Preliminary English Test: Student's Book. Newbury: Express Publishing, 2003.
Цитирование MLA (8-е изд.)Gray, Elisabeth, и Neil O'Sullivan. Practice Tests for the PET 1 Preliminary English Test: Student's Book. Express Publishing, 2003.
Предупреждение: эти цитированмия не могут быть всегда правильны на 100%.