1. World Health Organization. Health topics: Epidemiology. 2016.
http://www.who.int/topics/epidemiology/en/
.
2. Centers for Disease Control and Prevention. Principles of epidemiology in public health practice, third edition: an introduction to applied epidemiology and biostatistics. Section 1: definition of epidemiology. 2012.
http://www.cdc.gov/ophss/csels/dsepd/ss1978/lesson1/section1.html
.
3. University of Houston College of Education (ND). Descriptive epidemiology: person, place, and time.
http://viking.coe.uh.edu/~bsekula/pep7313/down/Ch.%204%20Friis.htm
.
4. Centers for Disease Control and Prevention. Principles of epidemiology in public health practice, third edition: an introduction to applied epidemiology and biostatistics. Section 7: analytical epidemiology. 2012.
http://www.cdc.gov/ophss/csels/dsepd/ss1978/lesson1/section7.html
.
5. Centers for Disease Control and Prevention. Principles of epidemiology in public health practice, third edition: an introduction to applied epidemiology and biostatistics. Section 1: definition of epidemiology. 2012.
http://www.cdc.gov/ophss/csels/dsepd/ss1978/lesson1/section4.html
.