Cita APA (7a ed.)

Ur, P. (1989). Grammar practice activities: A practical guide for teachers. Univ. Pr.

Cita Chicago Style (17a ed.)

Ur, Penny. Grammar Practice Activities: A Practical Guide for Teachers. Cambridge: Univ. Pr, 1989.

Cita MLA (9a ed.)

Ur, Penny. Grammar Practice Activities: A Practical Guide for Teachers. Univ. Pr, 1989.