"mouche, n." OED Online June 2003. Oxford University Press. Retrieved October 11, 2010: "a small patch of beard shaped and allowed to grow under the lower lip".
"Merriam-Webster Dictionary". Merriam-Webster Dictionary. Springfield, Massachusetts: Merriam-Webster Inc. Retrieved January 25, 2025. https://www.merriam-webster.com/dictionary/soul%20patch
Maggin, Donald L.: Dizzy: The Life and Times of John Birks Gillespie. HarperCollins, 2005
"The meaning of the soul patch: a brief history". Trivia Happy. Retrieved August 24, 2021. https://triviahappy.com/articles/the-meaning-of-the-soul-patch-a-brief-history