Prirodnii︠a︡t i ikonomicheskii︠a︡t potent︠s︡ial na planinite v Bŭlgarii︠a︡ = Prirodnyĭ i ėkonomicheskiĭ potent︠s︡ial gor Bolgarii = Natural and economic potential of the mountains in Bulgaria : v dva toma
Author
[redakt︠s︡ionna kolegii︠a︡ Kiril Mishev (otgovoren redaktor) and others]