
The UFO Phenomenon And Its Spiritual Background
The UFO-Phenomenon is just one way of meeting other realities into our daily-consciousness, beside ie. Out of Body Experience, Meditation (Higher-Self integration), Channeling and other influences of so called Paranormal, which is just the border of our own understanding of reality. 
The UFO-Phenomenon as indication of extraterrestrial presence, or as inner perception of a realization of subtle realities - the phenomenon is wide range. Here a more spiritual oriented approach to perceive the phenomenon:
EXTRATERRERSTRIAL CONTACT:
THE EVIDENCE AND IMPLICATIONS (Dr. Steven Greer)
Brief overview and introductions
UFO-FAQ (Steve Gamble)
UFO-FAQ-MINI (Steve Gamble)
Highly recommended FAQ with a lot of addresses and references UFO-GUIDE (Nick Humphries)
Who-is-who of UFO-society and their stories and backgrounds ET CONTACT: You Have All Had ET Contact (Lyssa Royal)
The main doorway through which many ETs choose to come to you is the door of the human consciousness . . .
MISC. ARTICLES
The Alien Question: An Expanded Perspective - A White Paper (Neil Freer)
Contactee: Billy Meier (James W. Deardorff, Wendelle Stevens)