@property<EOL><INDENT>def dbreference_types(self):<DEDENT>
q = self.session.query(distinct(models.DbReference.type_))<EOL>return [x[<NUM_LIT:0>] for x in q.all()]<EOL>
Distinct database reference types (``type_``) in :class:`.models.DbReference`

        :return: List of strings for all available database cross reference types used in model DbReference
        :rtype: list[str]