Тhе quasipotential approach to the syperfine splitting of muonic hydrogen and positronium

For the description of the two-partial atoms spectrum in quasipotential approach the relativistic amplitude is used. The interrelation of scattering amplitude expressions, corresponding to quantovoelektrodinamic corrections in various orders is traced. Arising from the accounting of delay effect the additional logarithmic corrections of the sixth order to the constant of fine structure in the bound level superfine shift are analyzed.