KALENDA, Česlovas. Ecological Problem: Content, Essence and Preconditions. Problemos, [S. l.], v. 58, p. 42–54, 2000. DOI: 10.15388/Problemos.2000.58.6808. Disponível em: https://www.zurnalai.vu.lt/problemos/article/view/6808. Acesso em: 7 nov. 2025.