@article{MZ_1942__48_169004,
     author = {O., Baier},
     title = {EIementarter {Beweis} der {Dreiecksungleichung} in der {Poincar\'eschen} {Halbebene}},
     journal = {Mathematische Zeitschrift},
     pages = {527--529},
     publisher = {mathdoc},
     volume = {48},
     year = {1942},
     zbl = {0027.12203},
     url = {http://geodesic.mathdoc.fr/item/MZ_1942__48_169004/}
}