OVSAK, Oksana - VYSOTSKA, Marina. External Economic Effects of Air Transport Development Due to the Liberalization. In Communications : Scientific Letters of the University of Zilina. - Žilina : EDIS, University Publishing House, University of Žilina, 2021. ISSN 1335-4205, 2021, vol. 23, no. 3, pp. A158-A173.