title: Air pollution and the 1974-1975 influenza epidemic in Sofia; a statistical study.
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D002031:Bulgaria; D004196:Disease Outbreaks / Q000453:epidemiology*; D004391:Dust / Q000032:analysis; D005557:Formaldehyde / Q000032:analysis; D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology*; D009609:Nitrous Oxide / Q000032:analysis; D010636:Phenols / Q000032:analysis; D012189:Retrospective Studies; D013458:Sulfur Dioxide / Q000032:analysis
chemical_list: D000393:Air Pollutants; D004391:Dust; D010636:Phenols; D013458:Sulfur Dioxide; D005557:Formaldehyde; D009609:Nitrous Oxide