APA

Keyes M., . (2006). Anybody out there?. london: Penguin books.

Chicago

Keyes Marian, . 2006. Anybody out there?. london: Penguin books.

Harvard

Keyes M., . (2006). Anybody out there?. london: Penguin books.

MLA

Keyes Marian, . Anybody out there?. london: Penguin books. 2006.