Developing gravity model for airline regional route modellingNõmmik, Allan; Kukemelk, SvenAviation2016 / p. 32-37 http://dx.doi.org/10.3846/16487788.2016.1168007 Do regional airlines in Eastern Europe have the right to survive in the European single sky environment?Kukemelk, SvenAviation2017 / p. 155-161 http://dx.doi.org/10.3846/16487788.2017.1415226