Macmillan, 1991
Buku Referensi
Gedes & Grosset, 2003
Buku Referensi
University of Technology Sydney
Lovell Johns , 1996
Buku Referensi
Rand McNally, editor
Time-Life Books, 1968
Buku Referensi
general editor Norman Myers ; foreword by Gerald Durrell ; featuring an extra chapter by Oxfam
Gaia Books, 1994
Buku Teks