These books offer detailed explorations of their title subjects. Cross-cultural, historical, and contemporary anecdotes will enthrall receptive readers. The texts are long and quite dense; half- to full-page stock photos and illustrations, along with pull-quotes and sidebars, add visual interest and help break up the pages, though the large images and their lengthy captions are often not placed with the text they support. Reading list, websites. Bib., ind.

Angels, King Arthur, and unicorns have all been subject to the Mysterious & Unknown series, which continues to put its magnifying glass to humankind's biggest question marks. Although the books may look standard at first glance, they are surprisingly exhaustive. Crop Circles is a perfect example w much is there to say about some crushed corn stalks? Plenty. Kallen reaches back to a 1678 account of a "Mowing-Devil" before considering numerous potential culprits: plasma vortexes, psychokinesis, UFOs, the military, and even wallabies stoned on opium. Equal time is spent between cereologists (those who study these formations) and plain old hoaxsters d both are equally interesting. Breakout summaries and quotes enliven the layout, and though illustrations of enticingly described evidence are sometimes omitted, there is still plenty of creepy stuff to scrutinize. Extensive notes and indexes conclude.