“…In most cases, these indicators are GDP, capital stock, and employment. Studies from the second group accentuate the importance of environmental issues (Streimikiene, 2016), employing economic and ecological indicators (Lovell et al, 1995;Zaim & Taskin, 2000;Zofio & Prieto, 2001;Arcelus & Arocena, 2005;Barla & Perelman, 2005;Camarero et al, 2008;Halkos & Tzeremes, 2009;Camarero et al, 2013;Lu et al, 2013). The undesirable indicators related to environmental problems are usually emissions to the environment, mostly carbon, nitrogen and sulphur.…”