TY  - JOUR 
T1  - Umbilic and Tangential Singularities on Configurations of Principal Curvature Lines
JO  - Anais da Academia Brasileira de Ciências
A1  - GARCIA, RONALDO
A1  - SOTOMAYOR, JORGE
SN  - 0001-3765
UL  - 10.1590/S0001-37652002000100001
VL  - 74 
Y1  - 2002
PB  - Brasil 
ER  -