Coxeter, H. S. M. (1985), "A special book review: M. C. Escher: His life and complete graphic work", The Mathematical Intelligencer, 7 (1): 59–69, doi:10.1007/BF03023010, S2CID189887063. See in particular p. 61.
Messina, Barbara; Chiarenza, Stefano (December 2020), "Drawing and geometric constructions of polyhedra in the art of Escher", in Cheng, Liang-Yee (ed.), ICGG 2020 - Proceedings of the 19th International Conference on Geometry and Graphics, Advances in Intelligent Systems and Computing, vol. 1296, Springer International Publishing, pp. 895–903, doi:10.1007/978-3-030-63403-2_81
Coxeter, H. S. M. (1985), "A special book review: M. C. Escher: His life and complete graphic work", The Mathematical Intelligencer, 7 (1): 59–69, doi:10.1007/BF03023010, S2CID189887063. See in particular p. 61.