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