@article{10_5427_jsing_2011_3h,
     author = {Goo Ishikawa and Yoshinori Machida, and Masatomo Takahashi},
     title = {Asymmetry in singularities of tangent surfaces in contact-cone {Legendre-null} duality},
     journal = {Journal of Singularities},
     pages = {126--143},
     publisher = {mathdoc},
     volume = {3},
     year = {2011},
     doi = {10.5427/jsing.2011.3h},
     url = {http://geodesic.mathdoc.fr/articles/10.5427/jsing.2011.3h/}
}