2. Dryzek, J., & Siemek, K. (2013). The accumulation effect of positrons in the stack of foils, detected by measurements of the positron implantation profile. J. Appl. Phys., 114, 224901–224906. DOI: 10.1063/1.4843035.10.1063/1.4843035
3. Dryzek, J., & Siemek, K. (2015). Positron accumulation effect in particles embedded in a low-density matrix. J. Appl. Phys., 117, 055901-7. DOI: 10.1063/1.4906400.10.1063/1.4906400