Gaya APA

Vallen, G, K., Vallen, J, J. (2005). Check-in chaeck-out : managing hotel operations (7th ed.). New Jersey: Pearson Prentice hall.

Gaya MLA

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