Karim, M. R., M. R. K. Sheikh, M. S. Islam, N. M. Salleh, and R. Yahya. “Synthesis, Crystal Structure, Mesophase Behaviour and Optical Property of Azo-Ester Bridged Compounds: Azo-Ester Bridged Compounds”. Journal of Scientific Research, vol. 11, no. 3, Sept. 2019, pp. 383-95, doi:10.3329/jsr.v11i3.41578.