Posamentier, A. S. (1996). Challnging Problems in Geometry. Dover Publications, inc.
Lua i Stíl Chicago (17ú heag.)Posamentier, Alfred S. Challnging Problems in Geometry. Dover Publications, inc, 1996.
Lua MLA (8ú heag.)Posamentier, Alfred S. Challnging Problems in Geometry. Dover Publications, inc, 1996.
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