Green functions of the anisotropic Heisenberg model

Single-particle Green's function in an anisotropic Heisenberg model

One-particle green s function in the anisotropic Heisenberg model

Single-particle Green's function in the anisotropic Heisenberg model II. Allowance for higher correlation functions

One self-consistent closure for chains of equations for Green's functions. An anisotropic heisenberg model

Exact set of equations for the Green's functions in the Heisenberg model

Correlation functions for anisotropic heisenberg model in zero magnetic field