Necessary density conditions for sampling and interpolation of certain entire functions

Duffin, R. J. &Shaeffer, A. C., A class of nonharmonic Fourier series.Trans. Amer. Math. Soc., 72 (1952), 341–366. Landau, H. J., A sparse regular sequence of exponentials closed on large sets.Bull. Amer. Math. Soc., 70 (1964), 566–569. — The eigenvalue behavior of certain convolution equations.Trans. Amer. Math. Soc., 115 (1965), 242–256. Loomis, L. H.,An Introduction to abstract harmonic analysis, Van Nostrand, New York, 1953. Riesz, F. &Sz.-Nagy, B.,Functional analysis, Ungar, New York, 1955. Shapiro, H. S. &Shields, A. L., On some interpolation problems for analytic functions.Amer. J. Math., 83 (1961), 513–532.