Buchari Alma
Alfabeta, 2007
Buku Teks
Lovelock, Christopher H.
Indeks, 2005
Buku Teks
Rambat Lupiyoadi
Salemba Empat, 2013
Buku Teks
Trisakti International Center for Service studies FE-Usakti, 2006
Majalah, Jurnal, Buletin
Rambat Lupiyoadi
Salemba Empat, 2001
Buku Teks