The first book was released on June 30th 1997, the second book was released on the 2nd of July 1998, the Third book was released on 8th July 1999 the fourth was released on the 8th if July 2000 the fifth book was released on the 28th of june 2003 the 6th book was released on the 16th of July 2005, and the last one was released on 21 of July 2007.