https://arxiv.org/abs/cond-mat/9511005
[cond-mat/9511005] Theory of Phonon-Assisted Multimagnon Optical Absorption and Bimagnon States in...
Abstract page for arXiv paper cond-mat/9511005: Theory of Phonon-Assisted Multimagnon Optical Absorption and Bimagnon States in Quantum Antiferromagnets