title: Quadratic response functions in the time-dependent four-component Hartree-Fock approximation.
authors.affiliation: Department of Physics and Measurement Technology, Linkoping University, SE-581 83 Linkoping, Sweden. panor@ifm.liu.se
authors.forename: Patrick
authors.initials: P
authors.lastname: Norman
authors.forename: Hans Jørgen Aa
authors.initials: HJ
authors.lastname: Jensen