Kudla, Ronald J.
Quorum Books, 1988
Buku Teks
Percerou, J.
Rousseau et Cie, Editeurs, 1935
Buku Teks
Comer, Ronald J
New York W.H. Freeman and Co. 1998,
Buku Teks
Busyra Azheri, author
RajaGrafindo Persada, 2012
Buku Teks
Compesi, Ronald J.
Allyn and Bacon, 1994
Buku Teks