APA

Snell H. M., Stone P. A. & Snell H. L. (1996). A summary of geographical characteristics of the Galápagos Islands. : .

Chicago

Snell Heidi M, Stone Paul A and Snell Howard L. 1996. A summary of geographical characteristics of the Galápagos Islands. : .

Harvard

Snell H. M., Stone P. A. and Snell H. L. (1996). A summary of geographical characteristics of the Galápagos Islands. : .

MLA

Snell Heidi M, Stone Paul A and Snell Howard L. A summary of geographical characteristics of the Galápagos Islands. : . 1996.