1. P. Hartman, Ordinary Differential Equations, Wiley, New York (1964).
2. S. Sternberg, “On the structure of local homeomorphisms of Euclidean n-space,” Amer. J. Math., 80, 623–631 (1958).
3. Jr. W. A. Harris and Y. Sibuya, “General solution of nonlinear difference equations,” Trans. Amer. Math. Soc., 115, 62–75 (1965).
4. B. K. Takano, “General solution of a nonlinear difference equations of Briot–Bouquet type,” Funkc. Ekvacioj., 13, No. 3, 179–198 (1971).
5. G. P. Pelyukh, “On the structure of continuous solutions of one class of nonlinear difference equations,” Differents. Uravn., 30, No. 6, 1083–1085 (1994).