SEARCH Articles Figures Tables Altered systems, perturbation theory Application of Perturbation Theory to Chemical Kinetic Systems Application of Perturbation Theory to Hydrogenic Systems Biological system perturbation Control of singularly perturbed systems Experimenter perturbing system Generalized perturbation theory homogeneous systems Independent systems perturbation Independent systems perturbation approach Interacting system perturbed Hamiltonian Metal system, perturbation Multiple Perturbation Theory for Many-Electron Systems and Properties Nervous system perturbation Nonstandard singularly perturbed systems with two time scales Nuclear spin system perturbation Perturbation Theory and the Study of Systems Close to Integrable Perturbation method three-orbital systems Perturbation theory Hamiltonian systems Perturbation theory degenerate systems Perturbation theory for altered systems Perturbation theory inhomogeneous systems Perturbation theory system quantum dynamics Perturbations, of cyclic systems Response of Systems to Pulse Perturbations Singularly perturbed system Singularly perturbed systems with three or more time scales Stationary Direct Perturbation Theory for Many-Electron Systems System perturbation Time-dependent perturbation theory, electron systems