Valkunas, L., Gruodis, A., Juodzbalis, D., Urbas, A., Durandin, A.D., Silinsh, E.A., Klimkans, A., and Larsson, S., Visible fluorescence on IR-excitation of polar dimethylaminobenzylidene 1,3-indandione crystals., Advanced Mat. Optics and Electronics, 2:221-232 1993