Thymidine, 2'-deoxy-P-thiocytidylyl-(5'-3')-P-thiothymidylyl-(5'-3')-2'-deoxy-P-thioguanylyl-(5'-3')-2'-deoxy-P-thiocytidylyl-(5'-3')-P-thiothymidylyl-(5'-3')-2'-deoxy-P-thiocytidylyl-(5'-3')-2'-deoxy-P-thiocytidy