Andrica, Dorin. “Some Remarks Concerning the Morse-Smale Characteristic of a Compact Manifold”. Rev. Anal. Numér. Théor. Approx. 21, no. 1 (February 1, 1992): 9–13. Accessed April 11, 2025. https://ictp.acad.ro/jnaat/journal/article/view/1992-vol21-no1-art2.