Bricmont, J., & Frohlich, J. (1987). STATISTICAL MECHANICAL METHODS IN PARTICLE STRUCTURE ANALYSIS OF LATTICE FIELD THEORIES. 3. CONFINEMENT AND BOUND STATES IN GAUGE THEORIES. Nuclear Physics, Section B, B280, 385-444. https://doi.org/10.1016/0550-3213(87)90154-4 (Original work published 1987)