public function getPingbacks()
    {
        $response = $this
            ->getHttpClient()
            ->request('GET', "/res.php?key={$this->apiKey}&action=get_pingback");

        $responseText = $response->getBody()->__toString();

        if (strpos($responseText, 'OK|') !== false) {
            $data = explode('|', $responseText);
            unset($data[0]);
            return empty($data[1]) ? [] : array_values($data);
        }

        throw new ErrorResponseException(
            $this->getErrorMessage($responseText) ?: $responseText,
            $this->getErrorCode($responseText) ?: 0
        );
    }