def referenceFile(self):
        try:
            return _FileReference( cmds.referenceQuery( self, f=1) )
        except RuntimeError:
            None
referenceQuery -file
dataset/ETHPy150Open CountZer0/PipelineConstructionSet/python/maya/site-packages/pymel-1.0.3/pymel/core/nodetypes.py/DependNode.referenceFile