1. Zur Lösung der diophantischen Gleichung m/n = 1/x + 1/y + 1/z insbesondere im Fall m = 4;Leon;J. reine angew. Math.,1962
2. Sur l'équation diophantienne 4/n = 1/x1 + 1/x2 + 1/x3;Obláth;Mathesis.,1949
3. On the diophantine equation 4/n = 1/x + 1/y + 1/z;Yamamoto;Mem. Fac. Sci. Kyushu University,1965
4. Sull'equazione diofantea 4/n = 1/x1 + 1/x2 + 1/x3;Rosati;Boll. Union Mat. Ital.,1954
5. On the number of solutions in positive integers of the equation yz +zx +xy = n;Mordell;Am. J. Math.,1923