TY - JOUR AU - J. C. F. Costa AU - L. F. Martins, AU - J. J. Nuño-Ballesteros TI - On the index of principal foliations of surfaces in R^3 with corank 1 singularities JO - Journal of Singularities PY - 2020 SP - 1 EP - 16 VL - 22 PB - mathdoc UR - http://geodesic.mathdoc.fr/articles/10.5427/jsing.2020.22a/ DO - 10.5427/jsing.2020.22a ID - 10_5427_jsing_2020_22a ER -