@article{MAN_1910__68_158445, author = {G. Sannia}, title = {Geometria differenziale delle congruenze rettilinee}, journal = {Mathematische Annalen}, pages = {409--416}, publisher = {mathdoc}, volume = {68}, year = {1910}, zbl = {41.0733.01}, url = {http://geodesic.mathdoc.fr/item/MAN_1910__68_158445/} }