Boyer & Grondzik have pulled together all of the disparate sources of information required to properly design an underground facility.
Although the book was written in 1987, there are no other books which have pulled together all of the design issues and formulas required to properly design a structure, including heating & ventilation, waterproofing techniques and studies of existing structures.
While people have been building and using underground housing for thousands of years, most of the published material consists of "how we did it" or analysis of ancient buildings. This is the first book I’ve found which brings the material required to properly engineer a design into one place.
The focus of the book is on the engineering aspects, so don’t expect much in the line of architectural design. Site selection, including soil types and proper detailing for passive solar heating, load balancing for heating & cooling systems, drainage system design and proper daylighting design are all covered very well.
This is not the ideal resource, I would like to see a more current book, which would give analysis of exiting structures over a longer time-frame (many of the structures analyzed were built during the "energy crisis" of the 70’s & early 80’s, and thus only had a decade or so of occupation.)
Overall, if you are interested in designing an underground home which will provide a safe, secure and low maintenance facility, this is a good reference. Oh, you might find you can easily design a "no-power" dwelling, at least as far as heating/cooling costs. Unless you like paying utility bills….
This is a technical book, some engineering knowledge is desirable when reading it, but it is not beyond the level of a high school student with some physics.