Free resources on God's sovereignty Pastor Walton recommends 2 books: The Sovereignty of God (by A. W. Pink) and Spurgeon's sermons on sovereignty (by C.H. Spurgeon).
A paperback edition of Pink's book is available free for the asking from Mount Zion Bible Church's Chapel Library (chapellibrary.org/literature/title-catalog) to individuals who request one.
Although they don't have Spurgeon's book available, they do have 5 booklets of his on the topic of Sovereignty: Election, Free Will - A Slave, God's Providence, Human Inability, and The Sea! The Sea! The Wide & Open Sea! Just search the same Web page with Author=Spurgeon and Topic=Sovereignty.
In addition to these free printed resources, they also have freely downloadable PDF files of them, as well as EPUB and MOBi files of some.