This volume presents lectures on new approaches to electron-electron and electron-phonon correlation effects in low-dimensional materials: organic solids, conducting polymers such as polyacetylenes (CH), organic and copper-oxide superconductors. Topics covered include the correlation effects in optical spectra, magnetic properties, nonlinear processes, electrons in 1-d and 2-d solids and their molecular components, new approaches to 1-d and 2-d Hubbard models, Peierls model, multiconfigurational approach to large systems, calculation of Madulung energy in complex crystals, quantum field model, and kink effects in optical spectra of high T superconductors.