APA

Heyn E. V., . (1972). A Century of wonders. New York: Doubleday & CO.

Chicago

Heyn Ernest V, . 1972. A Century of wonders. New York: Doubleday & CO.

Harvard

Heyn E. V., . (1972). A Century of wonders. New York: Doubleday & CO.

MLA

Heyn Ernest V, . A Century of wonders. New York: Doubleday & CO. 1972.