This book is a one-shot coloration between Marvel and DC in the early 80s. It featured two of the hottest teams (at the time) X-men and New Teen Titans as well as two villains, Dark Phoenix and Darkseid.
The Core has this listed under Uncanny X-men and the New Teen Titans. However the cover and indicia clearly state that this book is registered as Marvel and DC Presents featuring X-Men and the New Teen Titans.
So I believe this book should not be listed under “U” but under “M”.
Yes, I am trying to point out that the series is not “Uncanny X-Men and the New Teen Titans” but as listed in the indicia is actually “Marvel and DC Presents featuring X-Men and the New Teen Titans”.