NOVIKS, Gotfrīds. JAUNATNES EKOLOĢISKĀS IZGLĪTOŠANAS PROBLĒMAS. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference, Rezekne, Latvia, v. 1, p. 123–125, 1999. DOI: 10.17770/etr1999vol1.1893. Disponível em: https://journals.rta.lv/index.php/ETR/article/view/1893.. Acesso em: 28 apr. 2024.