Seek, and ye shall find...
This is a composite image from two separate sources.
The Doctor Strange portion of the image originally appeared on the cover of Doctor Strange #3, and was reproduced in black and white in Yaffa's Doctor Strange #1:
It also appeared earlier in Australia on the cover of Newton Comics' Doctor Strange #2:
The Hulk segment originally appeared in The Incredible Hulk #3 as a splash page (or part thereof):
This scan is from the first page of my Fireside softcover edition of The Incredible Hulk. I expect that similarly to the Doctor Strange splash page above, it was reproduced in black and white in Yaffa's The Incredible Hulk #1, but I don't have a copy to check.
I don't have a copy of either of the first two issues of Marvel's Greatest Comics! to check whether these two stories are also reproduced within. They may be, but I don't really expect to find that they are.