Roberts, D F Correspondence between Penrose and Roberts concerning sickle cell research, and between Penrose, Roberts and S P H Mandel (of Tulane University, New Orleans), concerning the paper "On the stability of haemoglobin gene frequencies in West Africa", by D F Roberts and A Boyo, Annals of Human Genetics, London (1960), 24, 375. A copy of the article is enclosed, alongside a handwritten explanation of the statistical analysis used. Oct 1954