I think I actually knew that at one time and was definitely having a moment.
With help from our friends at GCD, these are non-Barks covers
9
29
62
108
147
158
178
Interestingly, 178 was by Dan Gormley rather than Buettner. I'm not otherwise familiar with Gormley, although I like the 178 cover. In my view, Buettner was actually a good artist who ended up being overshadowed by Barks among duck fans.
I think Gormley drew Andy Panda and Howdy Doody covers as well. He did this drawings for a coloring book, I think. I have an early Centaur, The Arrow, with stories he drew.