Gaya APA
Vallen, J, J., Vallen, G, K. (2005).
Check-in chaeck-out : managing hotel operations (7th ed.).
New Jersey:
Pearson Prentice hall.
Gaya MLA
Vallen, Jerome, J.., Vallen, Gary, K..
"Check-in chaeck-out : managing hotel operations".
7th ed.
New Jersey:
Pearson Prentice hall,
2005.
BUKU.