VNET [21Vianet] SC 13G/A: UN ITED STATES SCHEDULE 13G AMENDMENT NO. 1
[UN ITED STATES SCHEDULE 13G AMENDMENT NO. 1 21Vianet Group, Inc. (Name of Issuer) Class A Ordinary Shares, par value $0.00001 per share (Title of Class of Securities) 90138A103 (CUSIP Number) Zhang Tian No.11 Jinrong Avenue, Xicheng District, Beijing, the PRC (Post Code: 100033) 86-10-66577333 (Name]