Densmore, Lyman Willard, Handbook of Hartwell Genealogy 1636-1887, An Account of the Descendants of William Hartwell of Concord Massachusetts. Boston: George E Crosby, 1887. M-LH UMI#G1043. Available at http://books.google.com/?id=CjotAAAAYAAJ. Also at http://catalog.hathitrust.org/Record/100509896. Information from this source tagged as [Ref: Densmore HARTWELL p[0-9]*].
Hazen, Henry A, History of Billerica, with Genealogical Register. Boston, MA: A Williams, 1883. LDS Film#0901880#2. Available at http://books.google.com/?id=OVunB0IQ_EcC Information from this source tagged as [Ref: Hazen Billerica p[0-9]*].
Sources with Information about marriage to David PARKER