A. El-Essawy, F.; I.M. Rady, S. Synthesis of Some N-Alkylated and 1,2,4-Triazole, 1,3,4-Oxa-, Thiadiazoles Containing 1H-Pyrazolo[3,4-b]pyridine Derivatives. ajc 2011, 23, 2461-2467.