Density, speed of sound, viscosity, refractive index and surface tension of N-methyl-2-pyrrolidone + diethanolamine (or triethanolamine) from T = (293.15 to 323.15)K López, A.B.; García-Abuín, A.; Gómez-Díaz, D.; La Rubia, M.D.; Navaza, J.M.; The Journal of Chemical Thermodynamics 2013, 61, 1-6