@article{700130,
     title = {Zur analytischen L\"osung alter und neuer geometrischer Optimierungsprobleme},
     booktitle = {Equadiff 6},
     series = {GDML\_Books},
     publisher = {J. E. Purkyn\v e University, Department of Mathematics},
     address = {Brno},
     year = {1986},
     pages = {[451]-458},
     mrnumber = {MR0881671},
     url = {http://dml.mathdoc.fr/item/700130}
}

Klötzler, Rolf. Zur analytischen Lösung alter und neuer geometrischer Optimierungsprobleme, dans Equadiff 6, GDML_Books,  (1986), pp. [451]-458. http://gdmltest.u-ga.fr/item/700130/