@article{PIM_1968_N_S_08_22_a20,
     author = {Stanimir Fempl},
     title = {Areol\"are {Exponentialfunktion} {Als} {L\"osung} {Einer} {Klasse} {Differentialgleichungen}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {138 },
     publisher = {mathdoc},
     volume = {_N_S_08},
     number = {22},
     year = {1968},
     url = {http://geodesic.mathdoc.fr/item/PIM_1968_N_S_08_22_a20/}
}