TY  - RPRT
TI  - Nonlinear sigma model at theta = pi : Euclidean lattice formulation and solid-on-solid models.
AU  - I Affleck
PY  - 1991
DO  - 10.1103/physrevlett.66.2429
UR  - https://pubmed.ncbi.nlm.nih.gov/10043486/
ID  - 10043486
ER  -