The Research on Environment Protection Knowledge and Competencies in Non-Formal Education. ENVIRONMENT. TECHNOLOGY. RESOURCES. Proceedings of the International Scientific and Practical Conference, [S. l.], v. 1, p. 235–239, 2015. DOI: 10.17770/etr2013vol1.808. Disponível em: https://archive-journals.rtu.lv/etr/article/view/3862.. Acesso em: 11 mar. 2026.