Urban factor and prevalence of respiratory symptoms and "angina ectoris". A study on 9,168 twin pairs with the aid of mailed questionnaires.
D000328:Adult; D000368:Aged; D000787:Angina Pectoris / Q000453:epidemiology*; D001991:Bronchitis / Q000453:epidemiology*; D003371:Cough / Q000453:epidemiology*; D004200:Diseases in Twins / Q000453:epidemiology*; D004777:Environment; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012494:Sampling Studies; D012907:Smoking; D013548:Sweden