In February 1970, Kickshaws editor David Silverman challenged the readers of Word Ways to find words such as ONION in which the letters preceding and succeeding a single core letter (in this case, the letter I) are the same. These were christened Heads 'n' Trails words by John Ferguson of Maryland. Silverman's idea was to find 26 of these words, each one having a different core letter. The exercise was dully completed, largely by Josepha Byrne in the May 1970 issue and Murray Pearce in the August 1971 one, using words of various lengths including ADA, EDGED, HOTSHOT and OUTSPOUTS.
Word Ways: Vol. 33
, Article 5.
Available at: https://digitalcommons.butler.edu/wordways/vol33/iss1/5