एपीए उद्धरण

Heyderman, E. (2010). Complete PET Student's book with answers. Cambridge University Press.

शिकागो स्टाइल उद्धरण

Heyderman, Emma. Complete PET Student's Book With Answers. Cambridge University Press, 2010.

एमएलए उद्धरण

Heyderman, Emma. Complete PET Student's Book With Answers. Cambridge University Press, 2010.