KITAZAWA, N. On Reeb graphs induced from smooth functions on $3$-dimensional closed manifolds which may not be orientable. Methods of Functional Analysis and Topology, [S. l.], v. 29, n. 1-2, p. 57–72, 2023. DOI: https://doi.org/10.31392/MFAT-npu26_1–2.2023.05. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/847. Acesso em: 15 dec. 2025.