Hubert A. Berens (1936-2015) Hubert Berens at the Mathematics Genealogy Project. Hubert Berens at Wikipedia (in German). Hubert Berens at MathSciNet (for those with access). Xu, Y., In Memoriam: Hubert A. Berens (1936-2015) , J. Approx. Theory 198 (2015), iv-xxix. For those with access, this article may be viewed at Science Direct.