@article{JRAM_1975__0274_0275_151571,
     author = {Ulrich Spengler and Hilger Wolff},
     title = {Die {L\"ange} einer symplektischen {Abbildung.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {150--157},
     publisher = {mathdoc},
     volume = {0274_0275},
     year = {1975},
     zbl = {0312.50012},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1975__0274_0275_151571/}
}