Variability in answers to a questionnaire on respiratory symptoms.
D001991:Bronchitis / Q000453:epidemiology*; D004194:Disease; D006306:Health Surveys; D006801:Humans; D012137:Respiratory System; D012140:Respiratory Tract Diseases; D011795:Surveys and Questionnaires
BRONCHITIS/epidemiology; HEALTH SURVEYS; RESPIRATORY SYSTEM/diseases