This issue has variants.
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). Original indexer cited Jack Kirby as layout artist.
Story of how Prof. X lost use of legs. Continued in X-Men 21.
Includes a letter from Frank Brunner