1. Baltzer, Richard,Die Elemente der Mathematik 2 (3rd. ed.). Hirzel, Leipzig, 1870.
2. Blundon, W. J.,Problem 260. Crux Mathematicorum4 (1978), 58–60.
3. Bottema, O., Djordjević, R. Z., Janić, R. R., Mitrinović, D. S. andVasić, P. M.,Geometric inequalities. Wolters-Noordhoff, Gronigen, 1969.
4. Coxeter, H. S. M.,The affine aspect of Yaglom's Galilean Feuerbach. Nieuw Arch. Wisk. (4),1 (1983), 212–223.
5. De Cicco, John,An analog of the nine-point circle in the Kasner plane. Amer. Math. Monthly46 (1939), 627–634.