def METHOD_NAME(cnum):
    """Query ES for conferences in the same series."""
    query = 'cnum:"{}"'.format(cnum)
    return LiteratureSearch().query_from_iq(
        query
    ).params(
        size=100,
        _source=[
            'control_number',
            'earliest_date',
            'titles',
            'authors',
            'publication_info',
            'citation_count',
            'collaboration'
        ]
    ).sort('-citation_count').execute().hits