MACHNIK, A. Chosen models of ecotourism in nature value areas in Poland. Geotourism/Geoturystyka, [S. l.], n. 21, p. 19, DOI: 10.7494/geotour.2010.21.19. Disponível em: https://journals.agh.edu.pl/geotour/article/view/978. Acesso em: 3 may. 2024.