Power of Three

Power of Three is the third of the six-book arcs of the Warriors series, and was published from 2007 to 2009. Its installments are as follows:
 * 1) The Sight (April 24, 2007)
 * 2) Dark River (December 26, 2007)
 * 3) Outcast (April 22, 2008)
 * 4) Eclipse (September 2, 2008)
 * 5) Long Shadows (November 25, 2008)
 * 6) Sunrise (April 21, 2009)