Birth certificate of Bertha Jeffreys, nee Swirles, b. 1903; marriage certificate of Bertha Swirles and Harold Jeffreys, 6 September 1940; birth certificate of Mercy Ellen Blaxley [one of B J's maternal aunts], 1893 [b. 24 Feb 1867]; Girton College Register entry for B J; biography of B J produced by NCUACS [National Cataloguing Unit for the Archives of Contemporary Scientists], 2007; will of B J, 21 October 1996; chronology of events in B J's life, 1903-96; list of B J's publications 1926-88; and 'The Blaxleys of Northampton and their Descendants' [family tree beginning with Mercy Lenton and Samuel Partridge Blaxley, who married in 1865 and whose 13 children included B J's mother, Harriett, and aunts Mercy, Clara and Bertha].