@article{AM2_1980__20_182374,
     author = {Halina Swiatak},
     title = {On an equation of information theory.},
     journal = {Aequationes mathematicae},
     pages = {18--22},
     publisher = {mathdoc},
     volume = {20},
     year = {1980},
     zbl = {0433.39010},
     url = {http://geodesic.mathdoc.fr/item/AM2_1980__20_182374/}
}