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Asthma - Symptoms and causes - Mayo Clinic
Asthma - World Health Organization (WHO)
Asthma | CDC - Centers for Disease Control and Prevention
Asthma: Types, Causes, Symptoms, Diagnosis & Treatment
Asthma - What Is Asthma? | NHLBI, NIH
Asthma: Causes, Symptoms, and Treatment - WebMD
Asthma - Diagnosis and treatment - Mayo Clinic
Asthma - Wikipedia
What Is Asthma? | American Lung Association
Asthma Clinic - Overview - Mayo Clinic