Steve Ray has a list of 35 loaded Questions for "Bible Christians" (quotation marks his)(link to the whole list). This is number 27/35. I'm trying to provide the answers in a common format, for easy reference.
27) If sola Scriptura is so solid and biblically based, why has there never been a full treatise written in its defense since the phrase was coined in the Reformation?
1) The phrase was not coined during the Reformation, though the phrase became a handy way of expressing the difference between the position of the Reformers as contrasted with the position of those who adhered to Trent.
2) William Whitaker wrote a full length treatise on the subject in the 1500's.
3) Since then, plenty of folks have written either full length treatises or large portions of larger treatises on the topic.
4) For example, William Webster and David King have a three volume set on the topic entitled, "Holy Scripture: the Ground and Pillar of the Faith," and Keith Mathison has a single volume that is entitle "The Shape of Sola Scriptura."