Herschel observations of extreme OH/IR stars - The isotopic ratios of oxygen as a sign-post for the stellar mass
K. Justtanont, M. J. Barlow, J. Blommaert, L. Decin, F. Kerschbaum, M. Matsuura, H. Olofsson, P. Owen, P. Royer, B. Swinyard, D. Teyssier, L. B. F. M. Waters and J. Yates
