On the Singular Direction of Entire Functions

In this paper, after defining a normal criterion with a parameter and a singular direction of an entire function corresponding to a normal criterion, we shall prove the following theorem.Theorem 1 Suppose that f(z) is a transcendental entire function. Then there exists a direction Δ: argz = θ0 (0≤0<2π) which is a singular direction of f(z) corresponding to every normal criterion with a parameter.From theorem 1 we deduce at once existence of some singular directions.