@Article{npg-13-621-2006,
AUTHOR = {Kostrykin, S. V. and Khapaev, A. A. and Ponomarev, V. M. and Yakushkin, I. G.},
TITLE = {Lagrangian structures in time-periodic vortical flows},
JOURNAL = {Nonlinear Processes  in Geophysics},
VOLUME = {13},
YEAR = {2006},
NUMBER = {6},
PAGES = {621--628},
URL = {http://www.nonlin-processes-geophys.net/13/621/2006/},
DOI = {10.5194/npg-13-621-2006}
}