@article{CMH_1970__45_139444,
     author = {Edgar Reich and Kurt Strebel},
     title = {On the {Extremality} of {Certain} {Teichm\"uller} {Mappings.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {353--362},
     publisher = {mathdoc},
     volume = {45},
     year = {1970},
     zbl = {0184.30903},
     url = {http://geodesic.mathdoc.fr/item/CMH_1970__45_139444/}
}