Trisecting a parallelogram
\textit{S. J. Maltby} [J. Comb. Theory, Ser. A 66, 40-52 (1994; Zbl 0797.05030)] proved that if a rectangle is dissected into 3 congruent pieces then those pieces must themselves be rectangles. In the present paper this result is generalized to parallelograms. The proof is elementary but not simple (8 lemmas, then the main theorem).
scientific article; zbMATH DE number 1836082