Numerical and Monte Carlo Bethe ansatz method: 1D Heisenberg model S.-J. Gu, N. M.R. Peres and Y.-Q. Li Eur. Phys. J. B, 48 2 (2005) 157-165 Published online: 16 December 2005 DOI: 10.1140/epjb/e2005-00390-1