However School Library Journal wrote `` Like many series , the `` Percy Jackson '' books are beginning to show the strain of familiarity and repetition . '' before adding : `` However , the overarching story line remains compelling , and the cliff-hanger ending will leave readers breathless in anticipation of the fifth and final volume . '' School Library Journal wrote that '' ( l ) ike many series , the `` Percy Jackson '' books are beginning to show the strain of familiarity and repetition '' , before adding `` However , the overarching story line remains compelling , and the cliff-hanger ending will leave readers breathless in anticipation of the fifth and final volume . ''