@article{JGG_2012_16_1_JGG_2012_16_1_a3,
     author = {M. K. Saad and G. Weiss },
     title = {Curvature {Lines} and {Normal} {Congruences} of {Triangular} {B�zier} {Patches}},
     journal = {Journal for geometry and graphics},
     pages = {29--4},
     publisher = {mathdoc},
     volume = {16},
     number = {1},
     year = {2012},
     url = {http://geodesic.mathdoc.fr/item/JGG_2012_16_1_JGG_2012_16_1_a3/}
}