Sources

Nichols--Lollis And Back fily tree

    John Sylvester Robert Grosvenor Eyre Marcy Flagg
    Spouse: Nancy Nannie K Monroe
    Father: Algernon Sidney Flagg
    Mother: Nancy Maria Marcy
    Children: Laura Marcy
    Birth: 6 Feb 1854 Massachusetts, USA
    Death: 11 Apr 1916 Wellesley, Norfolk, Massachusetts, USA
    Residence: 1880 Winchester, Middlesex, Massachusetts, USA

Death

Directory of Deceased American Physicians, 1804-1929 [database on-line].

Name: John S. Flagg
Death Date: 11 Apr 1916
Death Place: Wellesley, MA
Type Practice: Allopath

Publications

Family records of the descendants of Gershom Flagg (born 1730) of Lancaster, Massachusetts ...> p. 148 (1907)