The "Nine Marks of a Healthy Church" is a series of sermons by Mark Dever that has been published. There is a copywrite on the book; however, the sermons are available on the Capitol Hill Baptist Church website, for all to listen to (currently at no charge).
It should be noted that the sermons, though independant, build somewhat upon each other. Terefore, one should listen to them in order unless there is a specific matter (such as church discipline) that one needs another pastor's perspective on what the Bible says about that matter.
The links are provided here simply because so many people NECEP deals with have asked where they could find them.