[1] Hayman W. Meromorphic Function. Oxford: Clarendon Press, 1964

[2] Laine I. Nevanlinna Theory and Complex Differential Equations. De Gruyter Studies in Math, Vol 15. Berlin: Walter de Gruyter Inc, 1993
    

[3] Yang Lo. Value Distribution Theory. Beijing:  Science Press, 1993      
                     

[4] Gundersen G, Steinbart M. Subnormal solutions of second order linear differential equations with periodic
coefficients. Results in Math, 1994, 25: 270--289

[5] Wittich H. Subnormale Lösungen der Differentialgleichung w''+p(e^z)w'+q(e^z)w=0. Nagoya Math J, 1967, 30: 29--37

[6] Urabe H, Yang C C. On factorization of entire functions satisfying differential equations. Kodai Math J, 1991, 14: 123--133

[7] Yang Chungchun, Yi Hongxun. Uniqueness Theory of Meromorphic Functions. Dordrecht, Kluwer: Academic Publishers Group, 2003
     

[8] Gundersen G. Estimates for the logarithmic derivative of a meromorphic function, plus similar estimates. J London Math Soc, 1988, 37: 88--104

[9] Gundersen G. Finite order solutions of second order linear differential equations. Trans Amer Math Soc, 1988, 305: 415--429    

[10] Chen Zongxuan. On the growth of solutions of a class of higher order diffential equations. Chin Ann Math, 2003, 24B(4): 501--508

[11]  Chen Zongxuan. The growth of solutions of f''+e^-zf'+Q(z)f=0 where the order (Q)=1. Science in China (Series A), 2002, 45(3): 290--300
    

[12] Chen Zongxuan, Gao Shian, Shon Kwang Ho. On the dependent property of solutions for higher order periodic differential equations. Acta Math Sci, 2007, 27B(4): 743--752

[13] Chen Zongxuan, Yang Chungchun. Some further results on the zeros and growths of entire solutions of second order linear differential equations. Kodai Math J, 1999, 22: 273--285