APA

Keller U., . (1983). The building of the Panama Canal in historic photographs. Nueva York (Estados Unidos): Dover Publications.

Chicago

Keller Ulrich, . 1983. The building of the Panama Canal in historic photographs. Nueva York (Estados Unidos): Dover Publications.

Harvard

Keller U., . (1983). The building of the Panama Canal in historic photographs. Nueva York (Estados Unidos): Dover Publications.

MLA

Keller Ulrich, . The building of the Panama Canal in historic photographs. Nueva York (Estados Unidos): Dover Publications. 1983.