Thermodynamics of complexation of aqueous 18-crown-6 with rubidium and cesium ions: Apparent molar volumes and apparent molar heat capacities of aqueous (18-crown-6 + rubidium chloride) and (18-crown-6 + cesium chloride) at temperatures (278.15 to 393.15) K, at molalities (0.02 to 0.33) mol·kg−1, and at the pressure 0.35 MPa Ziemer, S.; Niederhauser, T.; Woolley, E.; The Journal of Chemical Thermodynamics 2006, 38, 323-336