A reversible word square is one in which every row can be read backwards, and every column upwards - see especially the examples in the second section below. Every word must be either a reversible word such as REVILER (RELIVER in reverse) or a palindrome, which is a special kind of reversible word. In this article, the term reversible word does not include palindromes. In general, counts include valid rotations and reflections.
Word Ways: Vol. 39
, Article 3.
Available at: http://digitalcommons.butler.edu/wordways/vol39/iss3/3