外接円
1929).
↑ De Villiers, Michael. "Equiangular cyclic and equilateral circumscribed polygons," Mathematical Gazette 95, March 2011, 102-107.
↑ Buchholz, Ralph H.; MacDougall, James A. (2008), “Cyclic polygons with rational sides and area”, Journal of Number Theory 128 (1): 17–48, doi:10.1016/j.jnt.2007.05.005, MR2382768, http://docserver.carma.newcastle.edu.au/785/ .