Many materials used in devices intended for converting the energy or information in its crystal structure belong to the layered ones. These materials include transition metal dichalcogenides, intercalated graphite compounds, semiconductors with superlattice, synthetic metals based on organic compounds, etc. This book examines the influence of non-parabolicity effects on magnetic, electric and thermoelectric properties of layered crystals with closed or transient Fermi surfaces, although most researchers believe that these effects can be pronounced only for high-open Fermi surfaces. The book can be recommended as a reference or textbook for undergraduate and graduate students of higher educational institutions as well as for professionals interested in the special problems of theoretical condensed matter physics.