@inbook{inbook34a7cc71,
title   = {Trajectories of magnetic field lines in tokamaks with helical windings},
author = {Caldas, Iberê Luiz and Heller, Maria Vittoria Adelina Prario and Camargo, S J and Andrade, M C R},
year = {1990},
publisher = {Plenum Press},
journal   = {Condensed Matter Theories}
}