Gee ". The leader of the group is Kim Taeyeon . The other members are Jessica Jung , Sunny , Tiffany , Kim Hyoyeon , Kwon Yuri , Choi Sooyoung , Im Yoona and Seohyun . Contents  [ hide ]  1 Career 1.1 2007–2008: Debut and Girls' Generation 1.2 2009: Gee ,