def get_reference_mcf(info):
    """Generate mcf line for all the reference properties."""
    reference_codes = ['ADR', 'ARX']
    # reference example in the dataset
    # ADR  PDB:6ZCZ
    # ARX  DOI:10.1101/2020.06.12.148387
    reference_map = {}
    for code in reference_codes:
        if code not in info:
            continue
        reference_string = info[code]
        database = reference_string.split(':')[0]
        id_num = reference_string[len(database) + 1:]
        reference_map[database] = id_num
    mcf_list = []
    database_to_property = {
        'PDB': 'rcsbPDBID',
        'Cellosaurus': 'cellosaurusID',
        'IMGT/mAb-DB': 'imgtMonoclonalAntibodiesDBID',
        'NeuroMab': 'neuroMabID',
        'ginas': 'ginasID',
        'RAN': 'recombinantAntibodyNetworkID',
        'Addgene': 'addgeneID',
        'PMID': 'pubMedID',
        'Patent': 'patentID',
        'DOI': 'digitalObjectID'
    }
    for database in reference_map:
        id_num = reference_map[database]
        if database not in database_to_property:
            return ''
        mcf_list.append(database_to_property[database] + ': "' + id_num + '"\n')

    return ''.join(mcf_list)