In 1964, NICAP published "The UFO Evidence", edited by Richard H. Hall, a summary of hundreds of unexplained reports studied by NICAP investigators through 1963. Sightings were systematically broken down by witness category and special types of evidence. For example, individual chapters were devoted to sightings by military personnel, pilots and aviation experts, and scientists and engineers. Another chapter was devoted to evidence of intelligent control and yet another to physical evidence or interactions, such as electromagnetic effects, radar tracking, photographs, sound, physiological effects, and so on. Another section examined observed patterns, such as descriptions of shape, color, maneuvers, flight behavior, and concentrations of sightings. The book is still considered an invaluable reference source in the field.