Alexander, L. G. (1977). New concept English. First thigs first. Longman.
Cita Chicago Style (17a ed.)Alexander, L. G. New Concept English. First Thigs First. Londres: Longman, 1977.
Cita MLA (9a ed.)Alexander, L. G. New Concept English. First Thigs First. Longman, 1977.
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