Cita APA

Obee, B., & Obee, B. (1999). The grammar activity book. Cambridge, UK: Cambridge University.

Citación estilo Chicago

Obee, Bob, y Bob Obee. The Grammar Activity Book. Cambridge, UK: Cambridge University, 1999.

Cita MLA

Obee, Bob, y Bob Obee. The Grammar Activity Book. Cambridge, UK: Cambridge University, 1999.