Citing Flowchart by Cardiff University Library Services is licensed under CC BY 4.0
Remember! If it's not your idea and it's not something most people know about, then you need to cite it.
Common knowledge refers to commonly known information about current events, famous people, geographical facts, or natural history; also, an easily observed or commonly reported fact or common saying.
Exception: if you use someone's words (for example, from a commentary, interpretation, analysis, etc.) even if they contain information that is common knowledge, you must cite the source.
Rule to follow: If in doubt, cite it.