@article{10_21136_CMJ_1967_100803,
     author = {Kurzweil, Jaroslav},
     title = {Van der {Pol} perturbation of the equation for a vibrating string},
     journal = {Czechoslovak Mathematical Journal},
     pages = {558--608},
     publisher = {mathdoc},
     volume = {17},
     number = {4},
     year = {1967},
     doi = {10.21136/CMJ.1967.100803},
     mrnumber = {0219863},
     zbl = {0164.41003},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1967.100803/}
}