Sigma International   LLC "Sigma-TM"   SIGMA POLYTEC PVT LTD   Sigma (Merck)   Sigma Aldrich Ireland Ltd   ZHEJIANG ESIGMA BIOTECHNOLOGY CO.,LTD.   ZHEJIANG ESIGMA ANIMAL HEALTH CO.LTD   ZhengDing County Sigma Chemical Co,Ltd   Sigma Minerals Limited   JI NAN SIGMA CHEMICAL CO,.LTD   Zhengzhou Sigma Chemical Co., Ltd.    Sigma Industrial Supplies   Sigma-Aldrich   ZHENGZHOU SIGMA CHEMICAL COP., LTD   Sigma   Chemsigma Int.Co.,Ltd.    Chemsigma Int. Co.,Ltd.   Sigma company   Sigma Aldrich India Pvt Ltd   ZhengDing County Sigma Chemical Co,Ltd