Nichols, Herbert L.
McGraw-Hill, 1976
Buku Referensi
Turner, Joe M.
McGraw-Hill, 2009
Buku Teks
Church, Horace K.
McGraw-Hill, 1981
Buku Referensi
Muccigrosso
Krieger publishing company, 2001
Buku Teks
Embassy of the United States of American, [date of publication not identified]
Buku Teks