Harahap, Sofyan Syafri
RajaGrafindo Persada, 1996
Buku Teks
Jones, Reginald L.
Taraporevala, 1966
Buku Teks
Banks, Alan
McGraw-Hill, 2008
Buku Teks
Wixon, Rufus
Alexander Hamilton Institute , 1961
Buku Teks
Pyhrr, Peter A.
John Wiley & Sons, 1973
Buku Teks