@other{https://resolver.caltech.edu/CaltechETD:etd-02022006-081545, title = "Observations of Perfect Potential Flow and Critical Velocities in Superfluid Helium ll", year = "1959", url = "https://resolver.caltech.edu/CaltechETD:etd-02022006-081545", id = "record", doi = "10.7907/AA2G-EP61" }