APA
Charles C. Colby ; Alice Foster, . (1931). Economic geography for secondary schools. Boston: Ginn and Company.
Chicago
Charles C. Colby ; Alice Foster, . 1931. Economic geography for secondary schools. Boston: Ginn and Company.
Harvard
Charles C. Colby ; Alice Foster, . (1931). Economic geography for secondary schools. Boston: Ginn and Company.
MLA
Charles C. Colby ; Alice Foster, . Economic geography for secondary schools. Boston: Ginn and Company. 1931.
