Bondar, M. V., O. V. Przhonska, O. D. Kachkovsky, A. Frazer, A. R. Morales, and K. D. Belfield. “New Fluorene-Based Fluorescent Probe With Efficient Two-Photon Absorption”. Ukrainian Journal of Physics, vol. 58, no. 8, Oct. 2018, p. 748, doi:10.15407/ujpe58.08.0748.