@article{CMH_1961__35_139216,
     author = {Christian Blatter},
     title = {\"Uber {Extremall\"angen} auf geschlossenen {Fl\"achen.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {153--168},
     publisher = {mathdoc},
     volume = {35},
     year = {1961},
     zbl = {0107.28404},
     url = {http://geodesic.mathdoc.fr/item/CMH_1961__35_139216/}
}