Heimildir

7.1 Höfuðsetning tölfræðinnar fyrir úrtaksmeðaltöl

Baran, D. (2010). 20 percent of Americans have never used email. WebGuild. Sótt af http://www.webguild.org/20080519/20-percent-of-americans-have-never-used-email

The Flurry Blog. (2013). Sótt af http://blog.flurry.com

U.S. Department of Agriculture. (án dags.). Sótt af https://www.usda.gov/

7.2 Höfuðsetning tölfræðinnar fyrir summur (valfrjálst)

Farago, P. (2012, 29. okt.). The truth about cats and dogs: Smartphone vs tablet usage differences. Flurry Analytics Blog. Sótt af http://flurrymobile.tumblr.com/post/113379683050/the-truth-about-cats-and-dogs-smartphone-vs

7.3 Notkun höfuðsetningar tölfræðinnar

The Wall Street Journal. (án dags.). Sótt af https://www.wsj.com/

Centers for Disease Control and Prevention. (2017, 16. apríl). National health and nutrition examination survey. National Center for Health Statistics. Sótt af http://www.cdc.gov/nchs/nhanes.htm