Ahmed, Gyulyay, Ivan Petkov, and Stoyan Gutzov. 2010. “Optical Properties of Sol-Gel Materials Doped With Ethyl 2-(7-Hydroxy-2-Oxo-2H-Chromen-4-Yl) Acetate”. European Journal of Chemistry 1 (4):259-61. https://doi.org/10.5155/eurjchem.1.4.259-261.187.