Speeds of Sound in Liquid and Supercritical Hexafluoropropylene (HFP) and Hexafluoropropylene Oxide (HFPO) at Pressures up to 400 MPa Lin, C.W.; Ramjugernath, D.; Reddy, P.; Trusler, J.P.M.; Journal of Chemical & Engineering Data 2012, 57, 2568-2575