@article{MM2_1984__47_155015,
     author = {Herbert Lange},
     title = {Higher secant varieties of curves and the theorem of {Nagata} on ruled surfaces.},
     journal = {Manuscripta mathematica},
     pages = {263--270},
     publisher = {mathdoc},
     volume = {47},
     year = {1984},
     zbl = {0578.14044},
     url = {http://geodesic.mathdoc.fr/item/MM2_1984__47_155015/}
}