JURGAITIS, Donatas. On simplification system of partial differential equations with variable . Lietuvos matematikos rinkinys, [S. l.], v. 42, n. spec., p. 178–183, 2002. DOI: 10.15388/LMR.2002.32877. Disponível em: https://www.journals.vu.lt/LMR/article/view/32877.. Acesso em: 20 may. 2024.