Son of Satan reveals himself to Dr. Strange in Giant-Sized Defenders #2.

Len Wein (w), Gil Kane (p), Klaus Janson (i), Glynis Wein (c), Dave Hunt (l), Roy Thomas (e), Giant-Sized Defenders, Vol 1, #2 (New York: Marvel Comics, Oct 1974), 26.

Mark Gruenwald, et al. (w), Official Handbook of the Marvel Universe: The Book of the Dead (Part 2) Vol 1, #14 (New York: Marvel Comics, March 1984), 16-17.