This is a list with KPop Girl Groups that debuted in 2009.
Some of the most famous K-Pop Girlgroups that debuted in 2009 are T-ara, 2NE1, f(x), SECRET, 4minute and After School, they were all girl groups that were very successful and with some of the best K-Pop discography. Many members of those groups became successful solo artists, like CL, Hyuna, Hyosung, Hyomin and Jiyeon.
Kpopalypse
A blog by kpopalypse about k-pop related stuff.
AsianJunkie
Quality K-Pop journalism and satire site.
r/kpop
Great source of K-Pop news and stuff
MV_DATABASE
Comprehensive K-Pop MV Playlists
Selca Kastden
Female K-Pop Idols Instagram and Twitter aggregator
Daisuki - Korean Music
K-Pop MV Database with YouTube views and various stats