In the May 1969 issue of Word Ways, David Silverman discusses Word Cycles. He says that "cycles of three ... are harder to come by, and cycles of two, e.g., BOAT HOUSE, are downright scarce". This is the kind of statement that immediately raises my hackles and sends me to the dictionary in search of a refutation, particularly when the problem seems so trivial.
Eckler, Faith W.
"A Second Look at Word Cycles,"
Word Ways: Vol. 3
, Article 13.
Available at: http://digitalcommons.butler.edu/wordways/vol3/iss1/13