@article{articlea919c417,
title   = {Simple umbilic points on surfaces immersed in 'R POT.4'},
author = {Vidalon, Carlos Teobaldo Gutiérrez and Guíñez, Víctor},
year = {2003},
doi = {10.3934/dcds.2003.9.877},
journal   = {Discrete and Continuous Dynamical Systems}
}