@other{https://resolver.caltech.edu/CaltechETD:etd-08212008-101113,
    title = "Interpretation of the neutral helium triplet spectrum in planetary nebulae",
    url = "https://resolver.caltech.edu/CaltechETD:etd-08212008-101113",
    id = "record",
    doi = "10.7907/FNVG-6W53"
}