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.
After the death of King Amaziah, the people of Judah crowned his son Uzziah king, even though he was only 16 at the time. Uzziah ruled 52 years from Jerusalem, the hometown of his mother Jecoliah. During his rule, he recaptured and rebuilt the town of Elath.