1. World Health Organization2012Depression: A Global Crisis. World Mental Health Day, October 10 2012 https://www.who.int/mental_health/management/depression/wfmh_paper_depression_wmhd_2012.pdf
2. American Psychiatric Association20162018-01-01What is Depression? https://www.psychiatry.org/patients-families/depression/what-is-depression
3. The increasing burden of depression
4. Depression and anxiety in chronic heart failure and chronic obstructive pulmonary disease: prevalence, relevance, clinical implications and management principles