Kuznietsova, I. V., and Yu. Yu. Soroka. “The First Betti Numbers of Orbits of Morse Functions on Surfaces”.
Ukrains’kyi Matematychnyi Zhurnal 73, no. 2 (February 22, 2021): 179–200. Accessed April 7, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/2383.