"Massachusetts, Births, 1841-1915," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/FX7T-LF6 : accessed 05 Oct 2014), Klaas Serwerda in entry for Bonkje Serwerda, 17 Sep 1896; citing Whitinsville, Worcester, Massachusetts, P. 538, L. 145, Massachusetts Archives, Boston; FHL microfilm 1843694.