We follow Good and Toulmin [Good, I. J., Toulmin, G. H., 1956, The number of new species and the increase in population coverage, when a sample is increased, "Biometrika" 63, pp. 45-63] and Efron and Thisted [Efron, Bradley, and Thisted, Ronald, 1976, Estimating the number of unseen species: how many words did Shakespeare know?, "Biometrika" 63, pp. 435-447] when we use the notation "V" ("vocabulary") and "S" ("species") to refer to the random variables of the numbers of types in sample and population respectively.
- Baayen & Lieber (2004), a pag.97