private function trackRefererSearchTerms($referer, $searchTerms)
    {
        $terms = [];

        foreach (explode(' ', $searchTerms) as $term) {
            $terms[] = $this->makeModel(BindingManager::MODEL_REFERER_SEARCH_TERM)->fill([
                'search_term' => $term,
            ]);
        }

        if (count($terms) > 0)
            $referer->searchTerms()->saveMany($terms);

    }