APA

Roberts J., . (2000). The Penguin history twentieth century. : Penguin books.

Chicago

Roberts J.M, . 2000. The Penguin history twentieth century. : Penguin books.

Harvard

Roberts J., . (2000). The Penguin history twentieth century. : Penguin books.

MLA

Roberts J.M, . The Penguin history twentieth century. : Penguin books. 2000.