In a continuation of my studies on alphabetical letters in five-letter words (see the May 1978 Kickshaws and "From AB--- to ---YZ" in the November 1978 issue) I present here an analysis of five-letter words containing each letter twice in all combinations. A glance at the tabulation will show that each letter must appear two times in each of ten words, for a total of 260 required.
Beaman, Ralph G.
"Twice in Fivers,"
Word Ways: Vol. 12
, Article 17.
Available at: https://digitalcommons.butler.edu/wordways/vol12/iss1/17