Amrose, James
John Wiley & Sons, 2000
Buku Teks
Parker, Harry
John Wiley & Sons, 1984
Buku Teks
Parker, Harry S.
John Wiley & Sons, 1991
Buku Teks
prepared by the Special Publications Division, National Geographic Society, Washington, D.C.
The National Geogarphic Society, 1986
Buku Referensi
Ambrose, James E.
John Wiley & Sons, c1979
Buku Teks