  The real and complex zeros of some special entire functions such as Wright,
hyper-Bessel, and a special case of generalized hypergeometric functions are
studied by using some classical results of Laguerre, Obreschkhoff, P\'olya and
Runckel. The obtained results extend the known theorem of Hurwitz on exact
number of nonreal zeros of Bessel functions of the first kind. Moreover,
results on zeros of derivatives of Bessel functions and cross-product of Bessel
functions are also given, which are related to some recent open problems.
