Temperature and Pressure Dependence of the Viscosity of the Ionic Liquids 1-Hexyl-3-methylimidazolium Hexafluorophosphate and 1-Butyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide Harris, K.R.; Kanakubo, M.; Woolf, L.A.; Journal of Chemical & Engineering Data 2007, 52, 1080-1085