  Free spinor fields, with spin 1/2, are explored in details in the momentum
picture of motion in Lagrangian quantum field theory. The field equations are
equivalently written in terms of creation and annihilation operators and on
their base the anticommutation relations are derived. Some problems concerning
the vacuum and state vectors of free spinor field are discussed. Several
Lagrangians, describing free spinor fields, are considered and the basic
consequences of them are investigated.
