Look up Lynn Margulis' work in this area.
Besides being Carl Sagan's ex-wife, she did a lot of good work in this area, much of it against bitter opposition from the biological establishment. She won.
Her book, "The Five Kingdoms", an introduction to taxonomy and a survey of all known life forms at the kingdom/phylum level, is a masterful and delightful read, as well as an excellent shelf reference.
Its available in paperback, I highly recommend it.