Gaya APA

Azar, 1, B, S., Hagen, 2, S, A. (2009). Understanding and Using English Grammar, Fourth Edition with Answer Key . New York: Pearson Education.

Gaya MLA

Azar, 1., Betty, S.., Hagen, 2., Stacy, A.. "Understanding and Using English Grammar, Fourth Edition with Answer Key". New York: Pearson Education, 2009. Book.