In the very first issue of Word Ways, published in February, 1968, an issue I had the honor of editing, I discussed word ladders, citing some interesting examples. Somewhat in the nature of a casual afterthoughts, I mentioned the fact that a seemingly very difficult problem was that of constructing a ladder to convert ABOVE into BELOW.
Borgmann, Dmitri A.
"Above and Below,"
Word Ways: Vol. 7
, Article 18.
Available at: http://digitalcommons.butler.edu/wordways/vol7/iss1/18