SEARCH Articles Figures Tables Approximation, two-body Dynamical Diffraction in Two Waves Approximation Polarization approximation (two molecules) Scattering atmospheres the two-stream approximation The Two-Centre Approximation Two-Electron Terms and the Douglas-Kroll-Hess Approximation Two-Point Approximate Orbital-Free Kinetic Energy Functionals Two-Point First Derivative Approximations Two-Temperature Approximation of CO2 Dissociation Kinetics in Non-Thermal Plasma Two-beam approximation Two-center approximation Two-centre approximation Two-compartment intravenous injection approximation with onecompartment model Two-flux approximation Two-level approximation Two-mode approximation Two-parameter approximation Two-spin approximation Two-state approximation Two-stream approximation