Zalman Reisen was a philologist of the Yiddish language, a historian of literature, an editor and translator into Yiddish, a biographer, author of textbooks, a literary critic, a writer and a journalist.
His most important work is the complete lexicon of Yiddish writers. In addition, he is one of the founders of the YIVO Institute.
His brother ia the author and poet Avraham Reyzen.
Full biography: Avraham Novershtern, "Reyzen, Zalmen" in The YIVO Encyclopedia of Jews in Eastern Europe website.