Disputed inker credit--Mike Esposito per Steve Whitaker and Nick Caputo, Joe Sinnott per the original indexer and Sinnott's personal records. Caputo believes Sinnott's records are in error and the cover is likely a combination of Esposito and Frank Giacoia, who often worked together on covers. Revised information by Caputo, Jan 2011.
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).