  A brief survey of the author's works on the quantum theory of magnetism.
Theoretical foundation and applications of the generalized spin-fermion (sp-d)
exchange lattice model to various magnetic systems, e.g., rare-earth metals and
compounds, and magnetic and diluted magnetic semiconductors are discussed
briefly. The main emphasis is put on the dynamic behavior of two interacting
subsystems, the localized spins and spin density of itinerant carriers. A
nonperturbative many-body approach was used to describe the quasiparticle
dynamics. The approach permits to investigate and clarify the role of various
interactions and disorder effects in combined quantum models of magnetism in
unified and coherent fashion.
