Gulac, O., L. Dubchak, I. Iarmolenko, and J. Yanchuk. “Cooperation of Ukraine and the European Union in the Ecological Sector: Directions and Prospects”. European Journal of Sustainable Development, vol. 8, no. 1, Feb. 2019, p. 22, doi:10.14207/ejsd.2019.v8n1p22.