Reaction of N1,N2-Diarylamidines with (2,3-Diphenylcyclopropen-1-ylidene)propanedinitrile: Synthesis of [2-Arylamino-4(1H)-pyridinylidene]-propanedinitriles - Gomaa, Mohsen A -M; Döpp, Dietrich (Synthesis, 2003)