Gaya APA

Katzung, B, G., Pendit, B, U. (2009). Understanding and using english grammar : with answer key (Ed. 4). Jena :: Pearson Education.

Gaya MLA

Katzung, Bertram, G.., Pendit, Brahm, U.. "Understanding and using english grammar : with answer key". Ed. 4 Jena :: Pearson Education, 2009. Text.