public function &GetFieldShopCategoryList($sOrderBy = '')
    {
        $oCategories = &$this->GetFromInternalCache('oCategories');
        if (is_null($oCategories)) {
            $oCategories = &TdbShopCategoryList::GetArticleCategories($this->id, $this->iLanguageId);
            $this->SetInternalCache('oCategories', $oCategories);
        }

        return $oCategories;
    }