APA

Pohl F., . (1990). Beyond the blue event Horizon. New York: Ballantine Books.

Chicago

Pohl Frederik, . 1990. Beyond the blue event Horizon. New York: Ballantine Books.

Harvard

Pohl F., . (1990). Beyond the blue event Horizon. New York: Ballantine Books.

MLA

Pohl Frederik, . Beyond the blue event Horizon. New York: Ballantine Books. 1990.