Masses and compositions of three small planets orbiting the nearby M dwarf L231-32 (TOI-270) and the M dwarf radius valley - Van Eylen, Vincent; Astudillo-Defru, N.; Bonfils, X.; Livingston, J.H.; Hirano, T.; Luque, R.; Lam, K. W.F.; Justesen, A.B.; Winn, J. N.; Gandolfi, D.; Nowak, G.; Palle, Enric; et al. (Monthly Notices of the Royal Astronomical Society, 2021)