APA

Hartman G., . (1959). Builders of the old world. Boston: D. C. Heath and Company.

Chicago

Hartman Gertrude, . 1959. Builders of the old world. Boston: D. C. Heath and Company.

Harvard

Hartman G., . (1959). Builders of the old world. Boston: D. C. Heath and Company.

MLA

Hartman Gertrude, . Builders of the old world. Boston: D. C. Heath and Company. 1959.