| Peter Lam 2020-04-25 , , medicalnewstoday, Retrieved 2020-09-23 | , National heart, lung and blood institute , Retrieved 2020-09-23 |
|---|---|
| Mayo Clinic Staff 2019-08-15 , , mayoclinic, Retrieved 2020-09-23 | Verneda Lights 2019-08-01 , , healthline, Retrieved 2020-09-23 |
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