GRAVER, B. (1971). Advanced english practice (2nd ed.). O.U.P.
Cita Chicago Style (17a ed.)GRAVER, B.D. Advanced English Practice. 2nd ed. London: O.U.P, 1971.
Cita MLA (9a ed.)GRAVER, B.D. Advanced English Practice. 2nd ed. O.U.P, 1971.
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