Helmut Heinrich Schaefer (February 14, 1925 in Großenhain, Weimar Republic – December 16, 2005 in Tübingen, Germany) was a German mathematician, who worked primarily in functional analysis. His two best known scientific monographs are titled ''Topological Vector Spaces'' (1966) and ''Banach Lattices'' ''and Positive Operators'' (1974). The first of these was subsequently translated into Spanish and Russian. The second made him an internationally recognized and leading scholar in this particular field of mathematics. (Roquette & Wolff, 2006)
Provided by Wikipedia