a) I have uploaded to http://www.cwru.edu/artsci/math/wells/pub/pdf/sketch.pdf a version of my 1993 sketches paper with an addendum listing a few relevant papers not included in the original work.   I have not kept up with the field well enough to contemplate a complete revision of the 1993 paper. b) There has recently been an uptick in citations to my paper [1]. Several works over the years ([2], [3], [4]) have given proofs of my theorem that are easier to understand and more informative, so I have posted a package here http://www.cwru.edu/artsci/math/wells/pub/pdf/AGEPackage.pdf that contains the original paper, a correction I published later, and the references below.  Malfait's article in particular embeds my exact sequence into a remarkable cube of exact sequences. [1] Charles Wells, Automorphisms of group extensions, Trans. Amer. Math. Soc, 155 (1970), 189-194. [2] Kung Wei Yang, Isomorphisms of group extensions.  Pacific J. Math. Volume 50, Number 1 (1974), 299-304. [3] D.J.S. Robinson, Applications of cohomology to the theory of groups, Groups – St. Andrews 1981, LondonMath. Soc. Lecture Notes vol. 71 (1982), pp. 46–80. [4] Wim Malfait, The (outer) automorphism group of a group extension. Bull. Belg. Math Soc. 9 (2002), 361-372. c) I recommend that more people update their papers in the manner I have updated these two. I did it by making a new PDF file with the added references and then using Acrobat to combine it with the old paper into one file.  That way I didn’t have to re-TeX the old paper (in the case of the sketches paper), which is a good thing, since I don’t know where some of the .sty files are. -- professional website: http://www.cwru.edu/artsci/math/wells/home.html blog: http://sixwingedseraph.wordpress.com/ abstract math website: http://www.abstractmath.org/MM//MMIntro.htm astounding math stories: http://www.abstractmath.org/MM//MMAstoundingMath.htm personal website:  http://www.abstractmath.org/Personal/index.html sixwingedseraph.facebook.com [For admin and other information see: http://www.mta.ca/~cat-dist/ ]