2 citations to https://www.mathnet.ru/rus/sm2640

1. Hyrien O., Yanev N.M., “Asymptotic Behavior of Cell Populations Described by Two-Type Reducible Age-Dependent Branching Processes with Non-Homogeneous Immigration”, Math. Popul. Stud., 19:4 (2012), 164–176        
2. Hyrien O., Yanev N.M., “Two-Type Reducible Age-Dependent Branching Processes with Non-Homogeneous Poisson Immigration”, C. R. Acad. Bulg. Sci., 64:4 (2011), 469–478