How does the character of David develop over the course of the books of Samuel and Kings?

The bible we are using is called Ignatius Bible, but we need three secondary sources. no online sources, only published books. He wants us to write about how david repenting from his sins helped him become a worthy hero. works cited page has to be on a separate page (3rd page) the essay has to be 2 full pages and the works cited on a new page. format for works cited has to be MLA. three sources. cannot be online sources. they have to be from a book