Cita APA

Brooke, H., & Helen Brooke. (1999). U.F.O.S. Oxford Bookworms Factfiles: Oxford University Press.

Chicago Style Citation

Brooke, Helen, i Helen Brooke. U.F.O.S. Oxford Bookworms Factfiles: Oxford University Press, 1999.

Cita MLA

Brooke, Helen, i Helen Brooke. U.F.O.S. Oxford Bookworms Factfiles: Oxford University Press, 1999.