Seagul Books, 2007
Buku Teks
Carl C. Taylor ... [and others]
Orient Longmans, 1965
Buku Teks
Rosen, George, author
University California Press, 1966
Buku Teks
Department of Economic Boston University , 1996
Buku Teks
Jamilah Nuh, author
2001
Artikel Jurnal