def getReffs(self, textId, level=1, subreference=None):
        """ Retrieve the siblings of a textual node

        :param textId: PrototypeText Identifier
        :type textId: str
        :param level: Depth for retrieval
        :type level: int
        :param subreference: Passage Reference
        :type subreference: str
        :return: List of references
        :rtype: [str]
        """
        return self.get_or(
            self.__cache_key_reffs__(textId, level, subreference),
            super(ProtoNautilusCtsResolver, self).getReffs, textId, level, subreference
        )