Renner, Michael
Worldwatch Institute, 1988
Buku Teks
Tiwari, Rajnish, author
East-West Center, 2011
Buku Teks
Campbell, Colin, author
Chapman and Hall, 1981
Buku Teks
Routledge, 1997
Buku Teks
edited by Geatoid O`Tuathail and Simon Dalby
Routledge, 1998
Buku Teks