JÄ™drzejczak-Gas, J., and A. Barska. “Assessment of the Economic Development of Polish Regions in the Context of the Implementation of the Concept of Sustainable Development - Taxonomic Analysis”. European Journal of Sustainable Development, vol. 8, no. 5, Oct. 2019, p. 222, doi:10.14207/ejsd.2019.v8n5p222.