public function getSource(ConnectionInterface $con = null)
    {
        if ($this->aSource === null && ($this->source_id != 0)) {
            $this->aSource = ChildSourceQuery::create()->findPk($this->source_id, $con);
            /* The following can be used additionally to
                guarantee the related object contains a reference
                to this object.  This level of coupling may, however, be
                undesirable since it could result in an only partially populated collection
                in the referenced object.
                $this->aSource->addPages($this);
             */
        }

        return $this->aSource;
    }