edited by Tensie Whelan; foreword by Peter A. A. Berle
New York : Uslan Press, 1991,
Buku Referensi
Simmons, I.G.
Routledge, 1993
Buku Teks
Island Press, 1991
Buku Teks
Laurie, Ian C.
Chichester: John Wiley & Sons, 1979
Buku Teks
Routledge, 1997
Buku Teks