Tham khảo Định_lý_lá_cờ_Anh

  1. ↑ Lardner, Dionysius (1848), The First Six Books of the Elements of Euclid, H.G. Bohn, tr. 87. Lardner includes this theorem in what he calls "the most useful and remarkable theorems which may be inferred" from the results in Book II of Euclid's Elements.
  2. ↑ Young, John Wesley; Morgan, Frank Millett (1917), Elementary Mathematical Analysis, The Macmillan company, tr. 304.
  3. ↑ Bôcher, Maxime (1915), Plane Analytic Geometry: with introductory chapters on the differential calculus, H. Holt and Company, tr. 17.
  4. ↑ Harvard-MIT Mathematics Tournament solutions, Problem 28.
  5. ↑ Hadamard, Jacques (2008), Lessons in Geometry: Plane geometry, American Mathematical Society, tr. 136, ISBN 978-0-8218-4367-3.
  6. ↑ Nguyễn Minh Hà và Đào Thanh Oai, An interesting application of the British flag theorem, Global Journal of Advanced Research on Classical and Modern Geometries, ISSN: 2284-5569, Vol.4, (2015), Issue 1, pp.31-34
  7. ↑ Dao Thanh Oai, Problem 2015.5, The Mathematical Gazette, 99, pp 554-556. doi:10.1017/mag.2015.108.