Planck 2015 results. XI. CMB power spectra, likelihoods, and robustness of parameters

P.A.R Ade, N. Aghanim, M. Arnaud, M. Ashdown, J. Aumont, C. Baccigalupi, A.J. Banday, R.B. Barreiro, J. G. Bartlett, N. Bartolo, Per Rex Christensen, Anne Mette Frejsel, Pavel Nasselski, Igor Dmitrievich Novikov, Hans Ulrik Nørgaard-Nielsen