Numerical Russian Dolls can be viewed as the numerical equivalent of Words in Words. The latter include ME inside COT in coMEt, RACE inside TRY in tRACEry and PEAK inside SING in sPEAKing. One word is surrounded by another, the latter being formed by bringing together letters from the beginning and end of the parent word.
"Numerical Russian Dolls,"
Word Ways: Vol. 47
, Article 9.
Available at: https://digitalcommons.butler.edu/wordways/vol47/iss2/9