Ward, P. D. (2004). Gorgon: The monsters that ruled the planet before dinosaurs and how they died in the greatest catastrophe in earth's history. Penguin Books.
Citace podle Chicago (17th ed.)Ward, Peter Douglas. Gorgon: The Monsters That Ruled the Planet Before Dinosaurs and How They Died in the Greatest Catastrophe in Earth's History. New York: Penguin Books, 2004.
Citace podle MLA (9th ed.)Ward, Peter Douglas. Gorgon: The Monsters That Ruled the Planet Before Dinosaurs and How They Died in the Greatest Catastrophe in Earth's History. Penguin Books, 2004.
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