Opportunistic transparent extension of a WLCG Tier 2 center using HPC resourcesR. Florian von Cube, René Caspart, Max Fischer, Manuel Giffels, Eileen Kuehn, Günter Quast and Matthias J. SchnepfEPJ Web Conf., 251 (2021) 02059DOI: https://doi.org/10.1051/epjconf/202125102059