Phase behaviour for the (CO2 + 1-butyl-2-pyrrolidone) and (CO2 + 1-octyl-2-pyrrolidone) systems at temperatures from (313.2 to 393.2)K and pressures up to 28 MPa Yim, J.H.; Choo, Y.S.; Byun, H.S.; The Journal of Chemical Thermodynamics 2019, 130, 140-146