Subharmonic solutions for hamiltonian systems via a ℤ p pseudoindex theory
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 4, Tome 15 (1988) no. 3, p. 357-409 
@article{ASNSP_1988_4_15_3_357_0,
     author = {Tarantello, Gabriella},
     title = {Subharmonic solutions for hamiltonian systems via a $\mathbb {Z}\_p$ pseudoindex theory},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     publisher = {Scuola normale superiore},
     volume = {Ser. 4, 15},
     number = {3},
     year = {1988},
     pages = {357-409},
     zbl = {0755.34035},
     mrnumber = {1015800},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1988_4_15_3_357_0}
}

Tarantello, Gabriella. Subharmonic solutions for hamiltonian systems via a $\mathbb {Z}_p$ pseudoindex theory. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 4, Tome 15 (1988) no. 3, pp. 357-409. http://www.numdam.org/item/ASNSP_1988_4_15_3_357_0/

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