public function getCrossFks()
    {
        $crossFks = [];
        foreach ($this->referrers as $refFK) {
            if ($refFK->getTable()->isCrossRef()) {
                $crossFK = new CrossForeignKeys($refFK, $this);
                foreach ($refFK->getOtherFks() as $fk) {
                    if ($fk->isAtLeastOneLocalPrimaryKeyIsRequired() &&
                        $crossFK->isAtLeastOneLocalPrimaryKeyNotCovered($fk)) {
                        $crossFK->addCrossForeignKey($fk);
                    }
                }
                if ($crossFK->hasCrossForeignKeys()) {
                    $crossFks[] = $crossFK;
                }
            }
        }

        return $crossFks;
    }