This issue has variants.
The on-sale date is the publication date reported in the U. S. Copyright Office filings.
Unaltered stats of this cover have been published in various reprints, including Marvel Masterworks: The X-Men Volume Three, 1987; the original version had no highlights on the Angel and different Cyclops, Marvel Girl and Iceman figures. Possible Severin alterations on The Angel per Nick Caputo.
Sources for letters credit are The Marvel Comics Index (Olshevsky 1981), The Official Marvel Index to the X-Men (Olshevsky 1987), The Official Marvel Index to the X-Men (Ward 1994), and Official Index to the Marvel Universe (Vandal et al. 2009).
First letters page. Includes Special Announcements Section.