J. M. Chwalek, C. Uher, J. F. Whitaker, G. A. Mourou, and J. A. Agostinelli, "Subpicosecond study of optical phonon oscillations in YBa2Cu3O6+x(x<0.4),"
in Quantum Electronics and Laser Science Conference, D. Auston, D. Chemla, T. McIlrath, and D. Steel, eds.,
Vol. 11 of OSA Technical Digest
(Optical Society of America, 1991), paper QTuE3.