http://owl.english.purdue.edu/owl/resource/560/01/
http://nutsandbolts.washcoll.edu/apa.html
http://writing2.richmond.edu/writing/wweb/apadocu.html
https://www.wlu.ca/forms/1691/How_to_Use_Sources_APA_%28revised%29.pdf
http://www.sass.uottawa.ca/writing/kit/reference-apa.php
http://web.psych.washington.edu/writingcenter/writingguides/pdf/howtocite.pdf
http://www.queensu.ca/writingcentre/handouts/APA.pdf
http://www.sdc.uwo.ca/writing/handouts/APA%20Style%20-%20Presentation.pdf