@article{MZ_1973__132_171932,
     author = {Erhard Heinz},
     title = {Elementare {Bemerkung} zur isoperimetrischen {Ungleichung} im {R3.}},
     journal = {Mathematische Zeitschrift},
     pages = {319--322},
     year = {1973},
     volume = {132},
     zbl = {0251.52014},
     url = {http://geodesic.mathdoc.fr/item/MZ_1973__132_171932/}
}