@other{https://resolver.caltech.edu/CaltechEERL:1961.EERL.1961.004,
    title = "Mode superposition methods applied to linear mechanical systems under earthquake type excitations",
    year = "1961",
    url = "https://resolver.caltech.edu/CaltechEERL:1961.EERL.1961.004",
    id = "record"
}