Gaya APA

Azar, B, S., Hagen, S, A. (2009). Understanding and Using English Grammar Fourth Edition with Answer Key (4). : Pearson Longman.

Gaya MLA

Azar, Betty, S.., Hagen, Stacy, A.. "Understanding and Using English Grammar Fourth Edition with Answer Key". 4 : Pearson Longman, 2009. Text.