More than two years since the release of her last album, pop superstar Christina Aguilera will be releasing a new single on August 13th, according to a report from Billboard.  A title for the track has yet to be released, but a source confirmed to Billboard that it was produced by Max Martin, who has helmed chart-toppers for artists like Britney Spears, Kelly Clarkson and Katy Perry.  In addition, the source told Billboard that Aguilera is working on duets with her fellow "The Voice" coaches Cee Lo Green and Blake Shelton, which will also be included on her next album.