Gaya APA

Training, I, O, E, L. (2011). Buku pintar IELTS (International English Language System) . Yogyakarta: Penerbit B First.

Gaya MLA

Training, Institute, Of, English, Language. "Buku pintar IELTS (International English Language System)". Yogyakarta: Penerbit B First, 2011. Text.