Merriam-Webster Dictionary defines plagiarism as follows:
According to the Online Learning Library of the University System of Georgia, common knowledge "is information that the majority of people either know or can find in a number of sources. Common knowledge is factual information that is beyond dispute. Sure, you might not remember (or ever have known) what Georgia's state bird is, but you can easily look it up in an almanac, encyclopedia, the state's Web site, or other resource. If you're not sure whether something is common knowledge or not, go ahead and provide a reference for it"
"Professor Eric Faden of Bucknell University created this humorous, yet informative, review of copyright principles delivered through the words of the very folks we can thank for nearly endless copyright terms"
From Stanford Law School, The Center for Internet and Society. Professor Faden's work is licenced under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License .