Gr 5-8 These titles begin with a definition of energy, describe its different forms and sources, and explain the problems with many of those sources. The author develops the focus of each book by discussing the specific energy source in terms of the technologies of harnessing it, its historical uses, its applications, and its limitations and problems. The first book presents a range of historical uses of the various forms of biomass, from charcoal smelters in ancient Egypt to ethanol-fueled lanterns in the 19th century and gasifiers during World War II. Vivid color photographs with informative captions extend the texts, showing diverse people and applications. In Sun , for example, the illustrations run the gamut from a woman in the Himalayas using a solar panel to heat her home to a modern office building with an entire wall covered in solar panels that run its computers, lights, and other equipment during the day. The books are mostly accurate, but the energy requirements of different appliances are given in terms of watts rather than watt hours/year, which would give a more realistic picture of the energy a given item uses. Overall, these volumes are good sources of information for researchers. As a set they provide a rounded picture of alternative sources of energy. Judith V. Lechner, Auburn University, AL