Bing found the following results
Asthma - Symptoms and causes - Mayo Clinic
Asthma - Diagnosis and treatment - Mayo Clinic
Asthma: Causes, Symptoms, and Treatment - WebMD
Asthma - World Health Organization (WHO)
Asthma | CDC - Centers for Disease Control and Prevention
Asthma - What Is Asthma? | NHLBI, NIH
What Is Asthma? | American Lung Association
Asthma: Symptoms, Treatment, and More - Healthline
Asthma attack - Symptoms and causes - Mayo Clinic
Asthma Information | Mount Sinai - New York