We are getting ready to build a greenhouse. It will be roughly 12' x 20'. Part of the materials will be doors and windows we salvaged during our 2006 remodel. But parts will either have to be scrounged, found or bought new. Has anyone read some good recent materials on greenhouse design and planning or built one recently? We have the original Solar Greenhouse book from 1976 as a guide, but it's a little dated in some areas.