The Book of Ruth: Its Structure, Theme and Purpose by Murray D. Gow

The book Ruth is recognized as one of the world's literary
masterpieces. Murray Gow's study illuminates the artistry of its anonymous
author, showing how the separate sections relate to the book as a whole.
Though Ruth is a moving story, it is also a presentation of God's
providence in which human agency and divine activity are intermeshed.
Against recent denials Murray Gow defends the traditional view that the
marriage of Ruth and Boaz is leviratic. He sees the book's purpose as
being to defend the Moabite element in the ancestry of King David and
concludes by offering suggestion as to its provenance, date and authorship.