@article{JRAM_1984__346_152584,
     author = {Herbert Lange},
     title = {On elementary transformations of ruled surfaces.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {32},
     publisher = {mathdoc},
     volume = {346},
     year = {1984},
     zbl = {0515.14008},
     language = {un},
     url = {https://geodesic-test.mathdoc.fr/item/JRAM_1984__346_152584/}
}