Orta, John, author
Garland Publishing, 1988
Buku Referensi
Hurt, R. Douglas, author
Garland Publishing, 1994
Buku Referensi
Rothschild, Bruce M., author
Springer, 2012
eBooks
United Nations Centre for Regional Development , 1983
Buku Teks
Klemstine, Charles F., author
Garland Publishing, 1984
Buku Teks