Physicochemical properties of two 1-alkyl-1-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide ionic liquids and of binary mixtures of 1-butyl-1-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide with methanol or acetonitrile Geppert-Rybczyńska, M.; Lehmann, J.K.; Heintz, A.; The Journal of Chemical Thermodynamics 2014, 71, 171-181