The oxygen isotope effect on the infrared photo-induced absorption spectra of La2CuO4R. V. Yusupov, K. Conder, T. Mertelj, D. Mihailovic, K. A. Müller and H. KellerEur. Phys. J. B, 54 4 (2006) 465-469DOI: https://doi.org/10.1140/epjb/e2007-00030-x