RUSCHEWEYH, S.; SALINAS, C. L. On the preservation of direction-convexity and the Goodman-Saff conjecture. Annales Fennici Mathematici, [S. l.], v. 14, n. 1, p. 63–73, 1989. DOI: 10.5186/aasfm.1989.1427. Disponível em: https://afm.journal.fi/article/view/134647. Acesso em: 25 nov. 2024.