Zylstra, Kirk D, author
PPM, 2006
Buku Teks
Lubis, Abdul Rahmat Firdaus, author
2017
UI - Skripsi (Membership)
Christopher, Martin, author
Prentice-Hall, 2005
Buku Teks
Bowersox, Donald J., author
McGraw-Hill, 2010
Buku Teks
Donald J. Bowersox [and three others]
McGraw-Hill, 2013
Buku Teks