TY - JOUR AU - R. Ballagh AU - John Cooper AU - W. Sandle BT - Journal of Physics B: Atomic and Molecular Physics DA - Apr-10-1983 DO - 10.1088/0022-3700/14/20/012 PY - 1981 SP - 3881 EP - 3890 T2 - Journal of Physics B: Atomic and Molecular Physics TI - Effective two-state behaviour of a collisionally perturbed Zeeman degenerate atomic transition and its application to optical bistability VL - 14 SN - 0022-3700 ER -