Entire functions of several variables of bounded $L$-index in direction and of bounded $\mathbf{L}$-index in joint variables

This monograph is devoted to the theory of entire functions of several variables. A definition of bounded index was supposed by B. Lepson. We generalised his definition for several variables and obtained criteria of L-index boundedness in direction. In particular we obtained obtain analogues of one-dimensional criterion of boundedness L-index in terms of behaviour the logarithmic derivative outside of zero sets, sufficient conditions of L-index boundedness in direction for some subclass of entire functions with "plane" zeros, sufficient conditions of L-index boundedness of entire solutions for some partial differential equations. Besides differential equations, entire functions of bounded index have application in the theory of value distribution. Bordulyak and Sheremeta's results about entire functions ob bounded $\mathbf{L}$-index in joint variables are also included.