Reprints begin with this issue and continue until issue #93.
in X-Men (K. G. Murray, 1970 series) #2 ([Circa 1970-1972])
in Marvel Masterworks: The X-Men (Marvel, 2003 series) #7 [Regular Edition] ([October] 2008)
in Marvel Firsts: The 1970s (Marvel, 2011 series) #1 (2011)
in Essential Classic X-Men (Marvel, 2006 series) #3 [black & white]Sources for Crespi letters credit are 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).
from The X-Men (Marvel, 1963 series) #12 (July 1965)
from The X-Men (Marvel, 1963 series) #13 (September 1965)