Źródło: | W: 17th International Multidisciplinary Scientific GeoConference. SGEM 2017, 29 June - 5 July 2017, Albena, Bulgaria. Conference proceedings. Vol. 17, Ecology, economics, education and legislation. Iss. 53, Environmental economics. Sofia : STEF92 Technology, 2017, s. 415-422, bibliogr. 15 poz. |