  A review of fundamental works by Shubin and Vonsovsky on the formulation of
the polar and s-d(f) exchange models is given. Their ideas are compared with
subsequent developments in the theory of magnetism in d- and f-metals and their
compounds. Modern approaches including different slave-boson and slave-fermion
representations, formation of exotic quasiparticles etc. are discussed.
Internal connections between various many-electron models (the Heisenberg,
Hubbard, t-J, Anderson Hamiltonians) are presented. Description of anomalous
rare-earth and actinide compounds (Kondo lattices, systems with heavy fermions
and non-Fermi-liquid behavior) within the framework of the s-d(f) exchange
model and related models is considered.
