Krasko, Evgeniy, and Alexander Omelchenko. “Enumeration of Chord Diagrams Without Loops and Parallel Chords”. The Electronic Journal of Combinatorics 24, no. 3 (September 8, 2017): P3.43. Accessed March 29, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v24i3p43.