(en) Telv Cohl, « A purely synthetic proof of Dao's theorem on six circumcenters associated with a cyclic hexagon », Forum Geometricorum, vol. 14, , p. 261–264 (ISSN1534-1178, lire en ligne).
geometry-math-journal.ro
(en) Nguyễn Minh Hà, « Another Purely Synthetic Proof of Dao's Theorem on Sixcircumcenters », Journal of Advanced Research on Classical and Modern Geometries, vol. 6, , p. 37–44 (ISSN2284-5569, lire en ligne)
(en) Nguyễn Tiến Dũng, « A Simple proof of Dao's Theorem on Sixcircumcenters », Journal of Advanced Research on Classical and Modern Geometries, vol. 6, , p. 58–61 (ISSN2284-5569, lire en ligne)
(en) Telv Cohl, « A purely synthetic proof of Dao's theorem on six circumcenters associated with a cyclic hexagon », Forum Geometricorum, vol. 14, , p. 261–264 (ISSN1534-1178, lire en ligne).
(en) Ngo Quang Duong, « Some problems around the Dao's theorem on six circumcenters associated with a cyclic hexagon configuration », International Journal of Computer Discovered Mathematics, vol. 1, , p. 25-39 (ISSN2367-7775, lire en ligne)
(en) Nguyễn Minh Hà, « Another Purely Synthetic Proof of Dao's Theorem on Sixcircumcenters », Journal of Advanced Research on Classical and Modern Geometries, vol. 6, , p. 37–44 (ISSN2284-5569, lire en ligne)
(en) Nguyễn Tiến Dũng, « A Simple proof of Dao's Theorem on Sixcircumcenters », Journal of Advanced Research on Classical and Modern Geometries, vol. 6, , p. 58–61 (ISSN2284-5569, lire en ligne)
journal-1.eu
(en) Ngo Quang Duong, « Some problems around the Dao's theorem on six circumcenters associated with a cyclic hexagon configuration », International Journal of Computer Discovered Mathematics, vol. 1, , p. 25-39 (ISSN2367-7775, lire en ligne)
(en) Nguyen Ngoc Giang, « The extension from a circle to a conic having center: The creative method of new theorems », International Journal of Computer Discovered Mathematics, , p. 21-32 (lire en ligne).