@article{Drzewiński:2009,
author
=
"A.Drzewiński and J.Sznajd",
title
=
"Real space renormalization group study of the anisotropic quantum Heisenberg model on a square lattice",
journal
=
"Physics Letters, Section A: General, Atomic and Solid State Physics",
volume
=
"Vol. 138",
number
=
"no 3",
pages
=
"143--146",
year
=
"1989",
}