D. V. Pilshchikov, “Estimation of the characteristics of time-memory-data tradeoff methods via generating functions of the number of particles and the total number of particles in the Galton–Watson process”, Матем. вопр. криптогр., 5:2 (2014), 103–108
Vatutin V.A., Sagitov S.M., “A Decomposable Critical Age–Dependent Branching–Process with 2 Types of Particles”, Doklady Akademii Nauk Sssr, 291:5 (1986), 1040–1043