@article{CMH_1969__44_139403,
     author = {Eugen Blum},
     title = {Die {Extremalit\"at} gewisser {Teichm\"ullerscher} {Abbildungen} des {Einheitskreises.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {319--340},
     publisher = {mathdoc},
     volume = {44},
     year = {1969},
     zbl = {0175.36901},
     url = {http://geodesic.mathdoc.fr/item/CMH_1969__44_139403/}
}