As for the rest of the acts of Jehoshaphat, from beginning to end, they are indeed written in the Chronicles of Jehu son of Hanani, which are recorded in the Book of the Kings of Israel.
KJV
Now the rest of the acts of Jehoshaphat, first and last, behold, they [are] written in the book of Jehu the son of Hanani, who [is] mentioned in the book of the kings of Israel.
ASV
Now the rest of the acts of Jehoshaphat, first and last, behold, they are written in the history of Jehu the son of Hanani, which is inserted in the book of the kings of Israel.