Analyses the age of references cited in source papers of the theoretic
al population genetics speciality at different phases bf its developme
nt. Discusses the characteristics of specialities in terms of obsolesc
ence measures such as half-life and immediacy index. Explores the appl
icability of different theoretical probability functions in the age de
nsities of references cited. Concludes that age of references cited is
best modelled according to lognormal distribution.