APA

Koebel W. H., . (1918). South America. London: T. Fisher Unwin.

Chicago

Koebel William Henry, . 1918. South America. London: T. Fisher Unwin.

Harvard

Koebel W. H., . (1918). South America. London: T. Fisher Unwin.

MLA

Koebel William Henry, . South America. London: T. Fisher Unwin. 1918.