Thread:Deathmanstratos/@comment-4495599-20130214000232/@comment-4495599-20130214010943

From Wikipedia:

An official anthology series, K-On! Anthology Comic (けいおん!アンソロジーコミック Keion! Ansorojī Komikku?), began sale from November 27, 2009, with five volumes released as of October 12, 2011, and two "Story Anthology Comics" were released on November 26, 2011.

And MAL.

Other authors' interpretations of Kakifly's original K-ON! 4koma strip.

"This is a K-ON! special. It consists of single-page 4-koma stories about K-ON! characters drawn by different mangaka."

That's what i found.