Dyfyniad APA

Powell, D., Walker, E., & Elsworth, S. (2008). Grammar Practice for Upper Intermediate Students: With key (Third Edition.). Pearson Education Limited.

Dyfyniad Arddull Chicago

Powell, Debra, Elaine Walker, and Steve Elsworth. Grammar Practice for Upper Intermediate Students: With Key. Third Edition. Essex, England: Pearson Education Limited, 2008.

Dyfyniad MLA

Powell, Debra, et al. Grammar Practice for Upper Intermediate Students: With Key. Third Edition. Pearson Education Limited, 2008.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.