Harrison, Roy M.
Whitstable Litho, 1982
Buku Teks
Crawford, Martin
Tata McGraw-Hill, 1976
Buku Teks
Clark, R.B.
Clarendon Press, 1986
Buku Teks
Davenport, S.J.
Washington, DC: United States Department of the Interior, 1954
Buku Teks
Frid, Christopher L. J.
Oxford University Press, 2017
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