@article{ZNSL_2003_300_a28,
     author = {O. \`E. Zubelevich},
     title = {On exponentially small effects in dynamical systems with a~small parameter},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {273--278},
     year = {2003},
     volume = {300},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2003_300_a28/}
}