According to the author of 2 Chronicles, all the important things that the king did are written in a special book about the kings of Judah and Israel. This means there are more stories and details about his life in another place.
2 Chronicles 28:26: Now the rest of his acts and of all his ways, first and last, behold, they [are] written in the book of the kings of Judah and Israel.
This verse might contain a contradiction in the historical account of King Ahaz's acts, providing a different perspective or missing details compared to 2 Chronicles 28:26.
2 Kings 16:19: Now the rest of the acts of Ahaz which he did, [are] they not written in the book of the chronicles of the kings of Judah?