Densities, speeds of sound, and refractive indices of the ternary mixtures (toluene + methyl acetate + butyl acetate) and (toluene + methyl acetate + methyl heptanoate) at 298.15 K Mariano, A.; Postigo, M.; González-Salgado, D.; Romaní, L.; The Journal of Chemical Thermodynamics 2007, 39, 218-224