In the August and November 1969 Word Ways, Ross and Faith Eckler presented a list of common trigrams that can be found in English words. They deserve congratulations, along with their helpers, for undertaking what, initially, must have appeared to be a Herculean task. They managed to track down 6,500+ of the 17,576 possible trigrams.
Word Ways: Vol. 4
, Article 16.
Available at: http://digitalcommons.butler.edu/wordways/vol4/iss1/16