@book{https://resolver.caltech.edu/CaltechAUTHORS:20130417-142619262,
    title = "Catalogue of Galaxies and of Clusters of Galaxies. Volume 6",
    year = "1968",
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130417-142619262",
    id = "record"
}


@book{https://resolver.caltech.edu/CaltechAUTHORS:20130418-114039281,
    title = "Catalogue of Galaxies and of Clusters of Galaxies. Volume 4",
    year = "1968",
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130418-114039281",
    id = "record"
}


@book{https://resolver.caltech.edu/CaltechAUTHORS:20130419-191042114,
    title = "Catalogue of Galaxies and of Clusters of Galaxies. Volume 3",
    year = "1966",
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130419-191042114",
    id = "record"
}


@book{https://resolver.caltech.edu/CaltechAUTHORS:20130418-114450113,
    title = "Catalogue of Galaxies and of Clusters of Galaxies. Volume 5",
    year = "1965",
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130418-114450113",
    id = "record"
}


@book{https://resolver.caltech.edu/CaltechAUTHORS:20130424-113656132,
    title = "Catalogue of Galaxies and of Clusters of Galaxies. Volume 2",
    year = "1963",
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130424-113656132",
    id = "record"
}


@book{https://resolver.caltech.edu/CaltechAUTHORS:20130417-133715737,
    title = "Catalogue of Galaxies and of Clusters of Galaxies. Volume 1",
    year = "1961",
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130417-133715737",
    id = "record"
}


@book{https://resolver.caltech.edu/CaltechAUTHORS:20200623-151845332,
    title = "Morphological Astronomy",
    year = "1957",
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20200623-151845332",
    id = "record",
    isbn = "978-3-642-87546-5",
    doi = "10.1007/978-3-642-87544-1"
}