gevorkyan, 1998, Hadronic atoms and positronium in the standard model, Workshop, 2
10.1103/PhysRevD.35.2124
10.1007/978-3-642-51185-1_2
10.1103/PhysRevA.48.3725
10.1016/0168-583X(95)01261-3
kunashenko, 1990, Yad Fiz, 51, 627
10.1016/S0375-9601(00)00342-X
10.1016/S0168-583X(98)00374-7
10.1016/0168-583X(95)01261-3
lyuboshits, 1987, Yad Fiz, 45, 682
ter-mikelian, 1972, High Energy Electromagnetic Processes in Condensed Media
olsen, 2033, Phys Rev D 33