@Article{336735,
     author = "Krystian Heffner, Brygida Solga",
     title = "Features of a migration region - an analysis using the example of the Opolskie Voivodship ",
     year =  2013,
     volume =  ,
     number =  20,
     journal =  Bulletin of Geography. Socio-Economic Series,
     pages =  s. 43-58,
    }