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Diakses pada 14 Februari 2019Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/esophageal-varices
Diakses pada 14 Februari 2019Medical News Today. https://www.medicalnewstoday.com/articles/320938.php
Diakses pada 14 Februari 2019Medical News Today. https://www.medicalnewstoday.com/articles/325109.php
Diakses pada 14 Februari 2019The National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/digestive-diseases/colon-polyps/definition-facts
Diakses pada 14 Februari 2019Verywell Health. https://www.verywellhealth.com/causes-of-black-stool-1941711
Diakses pada 14 Februari 2019