APA (7th ed.) Citation

Bergmann, P. G. (1968). The riddle of gravitation / by P.G. Bergmann. Scribner's.

Chicago Style (17th ed.) Citation

Bergmann, P. G. The Riddle of Gravitation / by P.G. Bergmann. Scribner's, 1968.

MLA (9th ed.) Citation

Bergmann, P. G. The Riddle of Gravitation / by P.G. Bergmann. Scribner's, 1968.

Warning: These citations may not always be 100% accurate.