Differential Geometry of a Surface at a Planar Point

V. G. Grove
1936 Transactions of the American Mathematical Society  
f Each branch of the curve of intersection of the surface with its tangent plane at a planar point of third order has at least four-point contact with its tangent line at the point. t E. Bompiani, Per lo studio proietlivo-differenziale dette singolarila, Bollettino dell' Unione Matemática, vol. 5 (1926), p. 118. Hereafter referred to as Bompiani. § E. P. Lane, Plane sections through an asymptotic tangent of a surface,
doi:10.2307/1989667 fatcat:slk4ukxvtbauldwir2cqu34jqu