B. Ágai, G. Hornyák, and K. Lempert, “PYRIMIDINES AND CONDENSED DERIVATIVES, III* THE SYNTHESIS OF SOME ISOCYTOSINES AND RELATED IMIDAZO[1,2-a]- AND -[1,2-c ]PYRIMIDINONES ”, Period. Polytech. Chem. Eng., vol. 18, no. 1, pp. 47–72, Jan. 1974.