Skerritt, Matt (June 27, 2003). "An Introduction to Knot Theory"(PDF). carmamaths.org. p. 22. Archived(PDF) from the original on November 19, 2022. Retrieved November 19, 2022.
Hodorog, Mădălina (February 2, 2010). "Basic Knot Theory"(PDF). www.dk-compmath.jku.at/people/mhodorog/. p. 47. Archived(PDF) from the original on November 19, 2022. Retrieved November 19, 2022.
Skerritt, Matt (June 27, 2003). "An Introduction to Knot Theory"(PDF). carmamaths.org. p. 22. Archived(PDF) from the original on November 19, 2022. Retrieved November 19, 2022.
Hodorog, Mădălina (February 2, 2010). "Basic Knot Theory"(PDF). www.dk-compmath.jku.at/people/mhodorog/. p. 47. Archived(PDF) from the original on November 19, 2022. Retrieved November 19, 2022.