Quantum electrodynamics within the framework of unified field theories -- Universality of lepton interactions -- Test of Quantum Electrodynamics at high momentum transfers -- Some basic problems of quantum electrodynamics -- The anomalous magnetic moment of the leptons: Theory and numerical methods -- Refined data on electron structure from invariant frequency ratios in electron and positron geonium spectra -- The muon magnetic moment -- The measurement of G-2 for the muon -- Quantum Electrodynamics in bound systems -- Ground state positronium: Hyperfine structure and decay rates -- Positronium in excited states -- Muonium and neutral muonic helium -- Vacuum polarization in muonic atoms -- The determination of Lamb shift from the anisotropy quenching radiation from metastable hydrogenic atoms -- The Lamb shift of the hydrogen atom and hydrogenic ions -- Helium and helium-like systems -- Comparison between experiment and theory in heavy electronic systems -- Positronenerzeugung bei Schwerionenstössen.