Citazione Stile APA (7a Edizione)

GRAVER, B. (1971). Advanced english practice (2nd ed.). O.U.P.

Citazione stile Chigago Style (17a edizione)

GRAVER, B.D. Advanced English Practice. 2nd ed. London: O.U.P, 1971.

Citatione MLA (9a ed.)

GRAVER, B.D. Advanced English Practice. 2nd ed. O.U.P, 1971.