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2. Yi, H.X. and Yang, C.C. (2003) Uniqueness Theory of Meromorphic Functions. Kluwer Academic Publishers, Dordrecht.
3. Complex Differences and Difference Equations
4. Nevanlinna Theory and Complex Differential Equations
5. Montel, P. (1927) Lecons sur les familles normales de fonctions analytiques et leurs applications. Gauthier Villars, Paris, 135-136.