Gaya APA
Smile, H. (2011).
Incredible and Impression Service : 156 Kebiasaan Efektif Orang Sales dan Customer Services .
Yogyakarta:
Shira Media.
Gaya MLA
Smile, Heri.
"Incredible and Impression Service : 156 Kebiasaan Efektif Orang Sales dan Customer Services".
Yogyakarta:
Shira Media,
2011.
.