Chemistry of 2-Arylhydrazonopropanals: Novel Synthesis of 1,6-Dihydropyridazines and 5-Heteroaryl Substituted Pyrazolo[1,5-a]Pyrimidines and Pyrazolo[3,4-b]Pyridines - Abdel-Khalik, Mervat Mohammed; Agamy, Samia Michel; Elnagdi, Mohammed Hilmy (Synthesis, 2001)