APA

Sivertsen E., . (1953). A new species of sea lion, Zalophus wollebaeki, from the Galápagos Islands. : .

Chicago

Sivertsen E, . 1953. A new species of sea lion, Zalophus wollebaeki, from the Galápagos Islands. : .

Harvard

Sivertsen E., . (1953). A new species of sea lion, Zalophus wollebaeki, from the Galápagos Islands. : .

MLA

Sivertsen E, . A new species of sea lion, Zalophus wollebaeki, from the Galápagos Islands. : . 1953.