Eisso J. Atzema, On n-sections and reciprocal quadrilaterals,
Forum Geometricorum, 9 (2009) 1--17.

Abstract:  We introduce the notion of an n-section and reformulate  a number  of standard Euclidean results regarding angles in terms of  2-sections (with proof).  Using 6-sections, we define the notion  of reciprocal (complete) quadrangles and derive some properties of  such quadrangles.

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