Hi Tim,
Thanks, I know about the Young--I traded it to you
Although I did not know it was your only one.
Barry, thanks for the kind words. I think I will wait a little longer and see what surfaces here before moving further on any article. For example, my view of the Mall Theater scarcity will shift noticeably if there are dozens of additional examples that can be at least quasi-confirmed by reputable sources. Mini-finds of one card back or another have popped up over the past 10-12 year so this should not be surprising.
Mark, thanks for the scan-- it was the last to elude me of those I listed.
Paul, thanks for the Zimmerman, and for shining the light on a possible list of others.
Any and all information greatly appreciated, as this topic is seldom discussed.