Synthesis of 5-Cyanopyrazolo[3,4-b]pyridines in the reaction of 5-Amino-3-methyl-1-phenylpyrazole with Arylidene derivatives of malonodinitrile and Ethyl Cyanoacetate - Quiroga, Jairo; Alvarado, Mario; Insuasty, Braulio; Moreno, Rodolfo; Ravina, Enrique; Estevez, Isabel; Santos, Regina Helena de Almeida (Journal of Heterocyclic Chemistry, 1999)