APA Style

Downie, M., Gray, D. (2015). English Elevator International : Intermediate Student's Book . : PT. ASTA ILMU SUKSES.

MLA Style

Downie, Michael., Gray, David. "English Elevator International : Intermediate Student's Book". : PT. ASTA ILMU SUKSES, 2015. Buku Pengayaan Khusus Siswa.