KABAILA, V. Die Existenzbedingungen der Lösung eines Gleichungssystems. Lithuanian Mathematical Journal, [S. l.], v. 4, n. 3, p. 353–356, 1964. DOI: 10.15388/LMJ.1964.19515. Disponível em: https://www.journals.vu.lt/LMJ/article/view/19515.. Acesso em: 6 may. 2024.