Sources

Biography here.

Name: Harihar Das Birth - Death: 1895-
Source Citation:

Concise Biographical Companion to Index Islamicus. An international who's who in Islamic studies from its beginnings down to the twentieth century. Three volumes. By Wolfgang Behn. Leiden, Netherlands: Koninklijke Brill, 2004-2006. (CnBCII)
Who Was Who among English and European Authors, 1931-1949. Based on entries which first appeared in The Author's and Writer's Who's Who and Reference Guide, originally compiled by Edward Martell and L.G. Pine, and in Who's Who among Living Authors of Older Nations, originally compiled by Alberta Lawrence. Three volumes. Detroit: Gale Research, 1978. (WhE&EA)
Who Was Who in Literature, 1906-1934. Based on entries that first appeared in Literary Yearbook (1906-1913), Literary Yearbook and Author's Who's Who (1914-1917), Literary Yearbook (1920-1922), and Who's Who in Literature (1924-1934). Two volumes. Detroit: Gale Research, 1979. (WhLit)

Death

Deaths Jun 1950
DAS Alarihar 55 Oxford 6b 853
Das Alarihar 55 Oxford 6b 853

As per author's biography in the posthumous work The Norris Embassy to Aurangzib, 1699-1702 (Pagelink, Worklink):

DOB: November 2, 1892

Place: Sidhipasa, Jessore district, Bengal

Father's name: J. C. Das, lawyer

Year shown as 1895 in Western sources, as in Who's Who in literature (1928)