Evidence for periodicity of swine influenza in Illinois--1963 to 1970.
D000367:Age Factors; D000818:Animals; D006385:Hemagglutination Inhibition Tests; D007087:Illinois; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D010507:Periodicity; D012621:Seasons; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control