The 2005 obituary published on tothewomen.org. It is the source that incorrectly gave Sophie’s birth date as January 21, 1922 — a three-week error that her own 1960 hand-written statement (which records February 12, 1922) corrects.
A useful piece of post-mortem narrative, but to be cited with caution: prefer Sophie’s own statement for the birth date and the names that appear in the obituary should be cross-checked.