1-Hydroxy-7-azabenzotriazole (HOAt) and N-[(dimethylamino)-1H-1,2,3-triazolo-[4,5-b]pyridin-1-yl-methylene]-N-methylmethanaminium hexafluorophosphate N-oxide (HATU) - Kienhöfer, Alexander (Synlett, 2001)