You can regard something as common knowledge IF:
But, when in doubt, cite. Your instructor will tell you if the citation turns out to be unnecessary,
#Use of Sources: Plagiarism
Plagiarism is all of the following:
--from Clemson Libraries
This video will demonstrate in 3 easy ways how to avoid plagiarism. (Skip any beginning ads/commercials.)
Find out more about plagiarism Frequently Asked Questions Regarding Plagiarism from Purdue Online Writing Lab (OWL).