@other{https://resolver.caltech.edu/CaltechTHESIS:03222013-082909262,
    title = "Nonlinear oscillations in discrete and continuous systems",
    year = "1978",
    url = "https://resolver.caltech.edu/CaltechTHESIS:03222013-082909262",
    id = "record",
    doi = "10.7907/tnnk-vh42"
}