John Gill's  Exposition of the Bible 

2 Kings 14:15

Now the rest of the acts of Jehoash which he did, and his might, and how he fought with Amaziah king of Judah, are they not written in the book of the chronicles of the kings of Israel?

Now the rest of the acts of Jehoash which he did, and his might,.... His valiant and mighty acts which he did in his wars with the Syrians, 2 Kings 13:25,

and how he fought with Amaziah king of Judah; a short account of which is given in the preceding verses:

are they not written in the book of the chronicles of the kings of Israel? a book very often mentioned and referred to, as containing the history of the events and transactions of every reign.