Gaya APA

Leo, S., Dewanti, R. (2017). English for profesional airline services (Cet. 1). Jakarta: Gramedia Pustaka Utama.

Gaya MLA

Leo, Sutanto., Dewanti, Retna. "English for profesional airline services". Cet. 1 Jakarta: Gramedia Pustaka Utama, 2017. Text.