Bergmann, Peter Gabriel. Introduction to the theory of relativity, by Peter Gabriel Bergmann ... with a foreword by Albert Einstein. - New York, Prentice-Hall, inc., 1942. - xvi, 287 p. diagrs. 24 cm. LCCN: 42014846 LC Class. No.: QC6 .B453 / .B453 Dewey Class. No.: 530.1