LHAPDF6: parton density access in the LHC precision eraAndy Buckley, James Ferrando, Stephen Lloyd, Karl Nordström, Ben Page, Martin Rüfenacht, Marek Schönherr and Graeme WattEur. Phys. J. C, 75 3 (2015) 132DOI: https://doi.org/10.1140/epjc/s10052-015-3318-8