A comparative analysis of the effects of natural and of radiation-induced lethals in heterozygous individuals and of their frequencies in natural populations of Drosophila Willistoni - Cunha, Antonio Brito da; Toledo, J. S. de; Pavan, Crodowaldo; Souza, H. L. de; Melara, H. E.; Gabrusewycz, N.; Gama, M. R.; Pires de Camargo, M. L.; Mello, L. C. de (Progress in Nuclear Research. Series 6, Biological Sciences, 1959)