I. A. Radini and A. H. F. Abd El-Wahab, “Heteroaromatization with 4-phenyldiazenyl-1-naphthol. Part I: Synthesis of some new naphthopyrans and naphthopyranopyrimidines”, Eur. J. Chem., vol. 7, no. 2, pp. 230–237, Jun. 2016.