Everything else Jehoash did while he was king, including his brave deeds and how he defeated King Amaziah of Judah, is written in The History of the Kings of Israel.
Amaziah was twenty-five years old when he became king, and he ruled twenty-nine years from Jerusalem, which was also the home town of his mother Jehoaddin.
After the death of King Amaziah, the people of Judah crowned his son Uzziah king, even though he was only sixteen at the time. Uzziah ruled fifty-two years from Jerusalem, the home town of his mother Jecoliah. During his rule, he recaptured and rebuilt the town of Elath.