Kelly's first bus was covered in our book Shelter (p. 89) in 1973, and his earthbag/papercrete house was in our book Home Work (p. 88) in 2004. He's been creating new mobile (and stationary) homes ever since. Plus running the info-packed website http://greenhomebuilding.com/.
The tone of writing is conversational and friendly, there are building tips for those inspired to do likewise, there are details and photos from a bunch of trips (including to Mexico), and there are a few hundred color photos. A homemade book in the best sense, made in the USA, $12 at Amazon here.