@article{articlea60192a7,
title   = {Nontwist symplectic maps in tokamaks},
author = {Caldas, Iberê Luiz and Viana, R L and Roberto, M and Martins, C G L and Szezech Jr., J D and Portela, J S E and Fonseca, J and Silva, E J da},
year = {2012},
doi = {10.1016/j.cnsns.2011.05.040},
journal   = {Communications in Nonlinear Science and Numerical Simulation}
}