Harold T. Wilkins in "Flying Saucers on the Attack", 1954:
[...]
Close to the place where the first atomic bomb was tested, a rancher at Roswell, New Mexico, was said, in July 1947, to have found a flying saucer. It landed in his ranch, and was inspected by officers of the 509th atomic bomb group of the 8th US Air Force who sent it to a 'higher quarter'.
[...]
Source:
In: "Flying Saucers on the Attack", book by Harold T. Wilkins, Ace Books publishers, USA, pp 66-67, 1954.