Elisabeth Kübler-Ross was a woman known for positing the Kübler-Ross model (commonly known as the five stages of grief) in her 1969 book, On Death and Dying. At some point, the Doctor had visited her and the two of them argued over the validity of her hypothesis. After an encounter with Ben Parsons on 23 November 1963, the Eleventh Doctor realised that the victims of the Shroud were demonstrating the five stages of grief (denial, anger, bargaining, depression, and acceptance), just like the ones Kübler-Ross later wrote about. (PROSE: Shroud of Sorrow)