There are periodically discussions on GLP in which people use material on wiki and other sites as proof that William Sadler wrote the Urantia Book. He did not and a number of years ago the TRUTH was buried somewhere on www.urantia.org. Much of the information that was once on that site has been removed. There was once a lot of discussion about a long term lawsuit and other issues for example and I had copied these to my older desktop and later found them GONE.
At any rate, the Urantia Book was given in exactly the same method as the Edgar Cayce teachings, thru a SLEEPING PROPHET, an individual who removed self and let another come thru his body. All of the papers were given thru the same individual, and his "secretary" took it all in SHORTHAND at the time, because there were no tape recorders yet. She then transcribed her own shorthand into the larger English, I am sure with celestial oversight on that one, so it was "right." The Sleeping Prophet could NEVER be made public at that time for a lot of very good reasons.
The papers were then presented to the study group who was behind the project and they were only allowed to correct mispellings or obvious grammer errors. Then the handwritten papers, once transribed to typewriter, were destroyed.
It required great care in those days to get these done and protected for the eventual printing of the book which occurred one year after Michael of Nebadon's return to this world. Getting it printed probably took a bunch of "miracles" under celestian efforts.
Also covered on the site at one time were the names of all the people who met and asked the questions that were then answered by the giving of the papers that became the book. No "man" wrote it.