public function referrerIsSearchEngine()
    {
        $referrerHostExploded = explode('.', $this->getReferrerDomain());
        $numberOfPieces = count($referrerHostExploded);
        $positionToCheck = $numberOfPieces - 2;

        if (!isset($referrerHostExploded[$positionToCheck])) {
            return false;
        }

        if (strlen($referrerHostExploded[$positionToCheck]) <= 3) {
            --$positionToCheck;

            if (!isset($referrerHostExploded[$positionToCheck])) {
                return false;
            }
        }

        return in_array(
            $referrerHostExploded[$positionToCheck],
            [
                'baidu',
                'bing',
                'bleikko',
                'duckduckgo',
                'exalead',
                'gigablast',
                'google',
                'munax',
                'qwant',
                'sogou',
                'yahoo',
                'yandex',
            ]
        );
    }