Hazel,
A little quick research paid off.
Maurice Doreal was born Claude Doggins in Sulphur Springs,
Oklahoma, in 1898.
He wrote "Mysteries of Mt. Shasta," "Mysteries of the Gobi," "Polar
Paradise," and other tract-type books.
He never went to Agharta, but in an effort to avoid atomic war,
Doreal gathered his followers in the late 1940s and retreated to
build "Shambala Ashrama" in the mountains of Colorado,
thirty-five miles southwest of Denver. He also called this city
"Western Shamballa, or Shangri-La in the Rockies."
According to Kafton-Minkel's book, there's a connection between
the writings of Doreal and "The Hefferlin Manuscript," which was
published in the Sept. 1946 issue of Amazing Stories (the same
pulp magazine which featured the Shaver Mystery) and was very
similar to Doreal's writings. This was written by W.C. Hefferlin.
Ray Palmer, who believed Shaver's tales, was suspicious of
Hefferlin's stories for a variety of reasons which are outlined in
the book.
For the full story, I strongly recommend Kafton-Minkel's book, as
it's filled with valuable information!
--Mike