The book is a step forward in the direction of the theory of analytic functions of a complex variable which is outstanding accomplishments of classical mathematics. Chapter three covers the definition of generalized logarithmic mean function and generalized logarithmic mean function of nth order of an entire Dirichlet series, and using these definitions some fruitful results are obtained. In chapter four, some growth relations of generalized logarithmic mean function and generalized logarithmic mean function of the nth derivative of an entire Dirichlet series are discussed. The relation between the orders of two entire functions is also obtained. The corollaries are also given in some theorems of this chapter. Further, this book includes some results for a class of entire functions of Dirichlet series.