[1] Bank S B. A note on the zeros of solutions of w''+P(z)w=0 where P is a polynomial. Appl Anal, 1987, 25: 29--41

[2] Bank S B, Laine I. On the oscillation theory of  f''+Af=0 where  A is entire. Trans Amer Math Soc, 1982, 273: 351--363

[3] Bank S B, Laine I, Langley J. On the frequency of zeros of solutions of secoond order linear differential equations. Results Math, 1986, 10: 8--24

[4] Fuchs W H J. Topics in Nevanlinna Theory. Proceedings of the NRL Conference on Classical Function Theory. Washington, DC: Naval Research Laboratory, 1970: 1--32

[5] Guncersen G G. On the real zeros of solutions of f''+A(z)f=0 where A(z) is entire. Ann Acad Sci Fenn Math, 1986, 11: 275--294

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

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

[8] Hayman W K. Meromorphic Functions. Oxford: Clarendon Press, 1964

[9] Hellerstein S, Rossi J. On the distribution of zeros of solutions of second-order differential equations. Complex Variables Theory Appl, 1989, 13: 99--109

[10] Hellerstein S, Miles J, Rossi J. On the growth of solutions of certain linear differential equations. Ann Acad Sci Fenn (Ser A I Math), 1992, 17: 343--365

[11] Hille E.  Lectures on  Ordinary Differntial Equations. California, London, Don Mills, Ontario: Addison--Wesley Publiching Company, Reading, Massachusetts-Menlo Park, 1969

[12] Rossi J, Wang S P. The radial oscillation of solutions to ODE's in the complex domain. Proc Edinburgh Math Soc, 1996, 39: 473--483

[13] Strodt W.  Contributions to the asymptotic theory of ordinary differential equations in the complex domain. Mem Amer Math Soc, 1954, 13: 22--34

[14]  Wu S J.  On the location of zeros of solution of f''+Af=0 where A(z) is entire. Math Scand, 1994, 74: 293--312

[15] Yang Lo.  Value Distribution Theory. Translated and Revised from the 1982 Chinese Original. Berlin: Springer-Verlag; Beijing: Science Press, 1993