GREKOV, Roman. DIRECT AND SUPPLEMENTARY SHADOWS IN THE TASK OF THE EFFICIENT DESCRIPTION OF CLASSES. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference, Rezekne, Latvia, v. 1, p. 32–32, 1999. DOI: 10.17770/etr1999vol1.1911. Disponível em: https://journals.ru.lv/index.php/ETR/article/view/1911.. Acesso em: 3 may. 2024.