Artikel Jurnal
Jansen Linardo, author
2017
UI - Makalah dan Kertas Kerja
Bodnar, George H., author
Prentice Hall International, 1995
Buku Teks
Sweeney, Robert B., author
Prentice-Hall, 1971
Buku Teks
Martin, Mearle, author
Prentice-Hall, 2003
Buku Teks