title: Factors in morbidity. Inter-practice variation of episodes of illness reported in the 1970--1971 national morbidity survey.
mesh_terms: D004739:England; D005194:Family Practice; D005260:Female; D006801:Humans; D008297:Male; D009017:Morbidity; D012042:Registries; D012111:Residence Characteristics; D014852:Wales