@article{CMH_1978__53_139738,
     author = {Kurt Strebel},
     title = {On quasiconformal mappings of open {Riemann} surfaces.},
     journal = {Commentarii mathematici Helvetici},
     pages = {301--321},
     year = {1978},
     volume = {53},
     zbl = {0421.30017},
     url = {http://geodesic.mathdoc.fr/item/CMH_1978__53_139738/}
}