Opdycke, J. B. (1941). Harper's English grammar. Harper & Brothers.
Lua i Stíl Chicago (17ú heag.)Opdycke, John B. Harper's English Grammar. New York ; London: Harper & Brothers, 1941.
Lua MLA (8ú heag.)Opdycke, John B. Harper's English Grammar. Harper & Brothers, 1941.
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