In the February 1968 Word Ways, Temple G. Porter presented a word chess puzzle; he asked readers to trace out as many words as possible using only King's moves on a 5-by-5 chessboard inscribed with 25 different letters. In the February 1970 issue, Jean Sabine posed an interesting and still unanswered chess problem: how should one arrange the 25 different letters to maximize the number of words that can be so traced?
Eckler, A. Ross
"Eodermdromes and Non-Chesswords,"
Word Ways: Vol. 14
, Article 19.
Available at: http://digitalcommons.butler.edu/wordways/vol14/iss4/19