Cita APA (7a ed.)

Christophersen, P., & Sandved, A. O. (1969). An advanced english grammar. Macmillan Education.

Cita Chicago Style (17a ed.)

Christophersen, Paul, y Arthur O. Sandved. An Advanced English Grammar. Londres: Macmillan Education, 1969.

Cita MLA (9a ed.)

Christophersen, Paul, y Arthur O. Sandved. An Advanced English Grammar. Macmillan Education, 1969.