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PDNTheoremForQuadrilateralCase.svg Diagram illustrating PetrDoglasNeumann theorem as applied to quadrilateral Krishnachandranvn talk created this work entirely by myself May UTC Krishnachandranvn talk Krishnachandranvn en Cczero Original upload log en PDNTheoremForQuadrilateralCase svg bytes Krishnachandranvn few changes