Cita APA (7th ed.)

Willis, D. (1998). Collins COBUILD Student's Grammar: Classroom Edition (Classroom ed.). HarperCollins Publishers.

Cita Chicago (17th ed.)

Willis, Dave. Collins COBUILD Student's Grammar: Classroom Edition. Classroom ed. London: HarperCollins Publishers, 1998.

Cita MLA (9th ed.)

Willis, Dave. Collins COBUILD Student's Grammar: Classroom Edition. Classroom ed. HarperCollins Publishers, 1998.