Uncanny X-Men Vol.1 #66
With Professor X in a coma after warding off the Z'Nox, the X-Men try to reach him and he mentally tells them one word, "Hulk"; The X-Men track down the jade giant and Jean's mental powers cause him to revert to Bruce Banner; Banner tells them that he has a machine that may save Xavier but Major Talbot shows up and causes him to transform to the Hulk again; The X-Men follow him into the desert and battle him at the site of an old lab where they are able to procure the piece of machinery that brings Professor X out of his coma.
Printed: Mar 1970
Writers: Roy Thomas
Art: Sal Buscema and Sam Grainger
Cover: Marie Severin and Sam Grainger