@other{https://resolver.caltech.edu/CaltechETD:etd-09042007-082903,
    title = "An experimental investigation on focussing of weak shock waves in air",
    url = "https://resolver.caltech.edu/CaltechETD:etd-09042007-082903",
    id = "record",
    doi = "10.7907/KK7V-6827"
}