Propagation Beats of Quadrupole Polaritons in Cu2O Fröhlich, D. ; Kulik, A. ; Uebbing, B. ; Langer, V. ; Stolz, H. ; von der Osten, W. Abstract Publication: Physica Status Solidi B Basic Research Pub Date: September 1992 DOI: 10.1002/pssb.2221730104 Bibcode: 1992PSSBR.173...31F