Riegel, R. E. (1948). Tests for United States of America. C. Scribner's Sons.
Lua i Stíl Chicago (17ú heag.)Riegel, Robert Edgar. Tests for United States of America. New York : Chicago [etc.]: C. Scribner's Sons, 1948.
Lua MLA (8ú heag.)Riegel, Robert Edgar. Tests for United States of America. C. Scribner's Sons, 1948.
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