I have a chapter on Whitlock in my book “The Invisible Art: The legends of Movie Matte Painting.” If you can buy the hardback that has a CD-Rom with a few Whitlock clips that was part of his demonstration reel. You can find it on Amazon or e-bay etc.
If you have a library that has “American Cinematographer” magazine look up “The Hindenburg” and “Earthquake” issues.
Also on the Stop Motion forum there is an active discussion on “Favorite Whitlock Matte Shots-
http://www.stopmotionanimation.com/dc/d ... =803&page=