Sumber:
Healthline. https://www.healthline.com/health/coughing-at-night
Diakses pada 10 Oktober 2019Medical News Today. https://www.medicalnewstoday.com/articles/319498.php
Diakses pada 10 Oktober 2019Web MD. https://www.webmd.com/cold-and-flu/features/nighttime-relief#1
Diakses pada 10 Oktober 2019