APA

Whitbeck R. H., Williams F. E., . (1940). Economic geography of South America. London: McGraw-Hill.

Chicago

Whitbeck R H, Williams Frank E, . 1940. Economic geography of South America. London: McGraw-Hill.

Harvard

Whitbeck R. H., Williams F. E., . (1940). Economic geography of South America. London: McGraw-Hill.

MLA

Whitbeck R H, Williams Frank E, . Economic geography of South America. London: McGraw-Hill. 1940.