Green devoted much of his time to historical studies and was librarian of the
Massachusetts Historical Society from 1868 until his death. and served as its vice-president from 1904 to 1918. In addition to a large number of papers on scientific and historical subjects, Green published: • ''My Campaigns in America: a Journal kept by Count William de Deux-Ponts, 1780-'1'', translated from the French manuscript, with an introduction and notes (Boston, 1868) •
An Account of Percival and Ellen Green and of Some of their Descendants (printed privately, Groton, Massachusetts, 1876) •
Epitaphs from the Old Burying-Ground in Groton, Massachusetts (1879) •
The Early Records of Groton, Mass., 1662-1677 (1880) •
History of Medicine in Massachusetts, a centennial address delivered before the
Massachusetts Medical Society at Cambridge, 7 June 1881 (Boston, 1881) •
Groton during the Indian Wars (Groton, 1883) •
Groton during the Witchcraft Times (1883) •
The Boundary-Lines of Old Groton (1885) •
The Geography of Groton, prepared for the use of the
Appalachian Mountain Club (1886) • "Groton Historical Series" (20 numbers, 1883-1887) == Later life ==