Towards an understanding of the Of?p star HD 191612: Optical spectroscopy

Ian D. Howarth, Nolan R. Walborn, Danny J. Lennon, Joachim Puls, Yaël Nazé, K. Annuk, I. Antokhin, D. Bohlender, H. Bond, J. F. Donati, L. Georgiev, D. Gies, D. Harmer, A. Herrero, I. Kolka, D. McDavid, T. Morel, I. Negueruela, G. Rauw, P. Reig