private function searchByProperties($propertyFilters, $rootClass, $offset, $limit)
    {
        // for searching by properties will be used RDF search
        $options = [
            'recursive' => true,
            'like'      => true,
            'limit'     => $limit,
            'offset'    => $offset
        ];
        $count = $rootClass->countInstances($propertyFilters, $options);
        $resources = $rootClass->searchInstances($propertyFilters, $options);
        return $this->format($resources, $count, $offset, $limit);
    }