A determination of the charm content of the proton - The NNPDF Collaboration Richard D. Ball, Valerio Bertone, Marco Bonvini, Stefano Carrazza, Stefano Forte, Alberto Guffanti, Nathan P. Hartland, Juan Rojo and Luca Rottoli Eur. Phys. J. C, 76 11 (2016) 647 Published online: 24 November 2016 DOI: 10.1140/epjc/s10052-016-4469-y