@article{MAN_1935__111_159794,
     author = {B. Ramamurti},
     title = {On rational normal ruled surfaces},
     journal = {Mathematische Annalen},
     pages = {582--586},
     publisher = {mathdoc},
     volume = {111},
     year = {1935},
     zbl = {61.0717.01},
     url = {http://geodesic.mathdoc.fr/item/MAN_1935__111_159794/}
}