Crossley, J. N. (1990). What is mathematical logicn QA9 .W. Dover Publications.
Lua i Stíl Chicago (17ú heag.)Crossley, John N. What Is Mathematical Logicn QA9 .W. New York: Dover Publications, 1990.
Lua MLA (9ú heag.)Crossley, John N. What Is Mathematical Logicn QA9 .W. Dover Publications, 1990.
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