I saw it with my own eyes when I was in his office to discuss some typesetter-interfacing issues, but I suppose that&#x27;s not enough of a reference. Perhaps the story is repeated in an old issue of TuGboat, the journal of the TeX Users Group, but I couldn&#x27;t find it.  Here&#x27;s a more extensive description from a decade ago though: <a href="https:&#x2F;&#x2F;groups.google.com&#x2F;d&#x2F;msg&#x2F;comp.text.tex&#x2F;9quGg7j6U0k&#x2F;tlWm_B_zQ5IJ" rel="nofollow">https:&#x2F;&#x2F;groups.google.com&#x2F;d&#x2F;msg&#x2F;comp.text.tex&#x2F;9quGg7j6U0k&#x2F;tl...</a>