APA

Bergmann P. G., . (1968). The riddle of gravitation. New York: Scribner.

Chicago

Bergmann Peter Gabriel, . 1968. The riddle of gravitation. New York: Scribner.

Harvard

Bergmann P. G., . (1968). The riddle of gravitation. New York: Scribner.

MLA

Bergmann Peter Gabriel, . The riddle of gravitation. New York: Scribner. 1968.