Opp, Christian, Bastian Ziebolz, and Michael Groll. 2018. “Ecological, Socio-Economic and Demographic Analyses As Prerequisites for Sewage Treatment Problem Solutions in Rural Areas. The Case Study of Dirlammen, Vogelsberg, Germany”. DIE ERDE – Journal of the Geographical Society of Berlin 149 (2-3):184-97. https://die-erde.de/index.php/die-erde/article/view/369.