@article{RLINA_1979_8_67_1-2_a9,
     author = {Obi, Chike},
     title = {Analytical theory of nonlinear oscillations $X$: some classes of equations $\ddot x + g(x) = 0$ with no finite {Fourier} series solution},
     journal = {Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali},
     pages = {53--56},
     publisher = {mathdoc},
     volume = {Ser. 8, 67},
     number = {1-2},
     year = {1979},
     zbl = {0469.34004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RLINA_1979_8_67_1-2_a9/}
}