WILLIAMS, F. L. A tractroid realization of a 2d black hole vacuum. Annals of Mathematics and Physics, [S. l.], v. 5, n. 2, p. 097–099, 2022. DOI: 10.17352/amp.000046. Disponível em: https://www.peertechzpublications.us/amp/article/view/AMP-5-146. Acesso em: 10 jan. 2025.