public static function getBySlug(Bookboon $bookboon, string $slug, array $bookTypes = ['pdf']) : BookboonResponse
    {

        /** @var Frontpage[] $frontpageArray */
        $bResponse = $bookboon->rawRequest("/frontpage/$slug", ['bookType' => join(',', $bookTypes)]);

        $bResponse->setEntityStore(
            new EntityStore(
                [
                    new static($bResponse->getReturnArray())
                ]
            )
        );

        return $bResponse;
    }