1. G. Lüders:Zeits. Naturf.,10 a, 581 (1955);A. Martin:Compt. Rend.,243, 22 (1956).
2. E. P. Wigner:Phys. Rev.,98, 145 (1955).
3. R. P. Boas jr.:Entire Functions (New York, 1954).
4. This class has been introduced byYa. Levin. See (3),R. P. Boas jr.:Entire Functions (New York, 1954). p. 129.
5. See (3),R. P. Boas jr.:Entire Functions (New York, 1954). p. 129, Theorem 7.8.1.