Rhonda Phillips, Robert H. Pittman, editor
Routledge, 2009
Buku Teks
McGraw-Hill, 1976
Buku Teks
edited by Mahlon Apgar
McGraw-Hill, 1976
Buku Teks
Foundation for Rural Education and Development (FRED) (June 12, 1999, 1999
Buku Teks
United Nations Bureau of Social Affairs , 1955
Buku Teks