A. O. Abdelhamid, A. A. Fahmi, and A. B. Ali, “Reactions with hydrazonoyl halides 66: Synthesis of some new 1,3,4-thiadiazoles, triazolino[4,3-a]pyrimidines and isoxazolo[3,4-d]pyridazines containing coumarin moiety”, Eur. J. Chem., vol. 2, no. 4, pp. 544–551, Dec. 2011.