1. Holm S. The debate about physician assistance in dying: 40 years of unrivalled Progress in medical ethics? J Med Ethics. 2015;40:40–3.
2. Garrard E, Wilkinson S. Passive euthanasia. J Med Ethics. 2005;31:64–8.
3. Rachels J. Active and passive euthanasia. In: Rachels J, editor. Can ethics provide answers? Lanham: Rowman and Littlefield; 1997.
4. Rachels J. The end of life. Oxford: Oxford UP; 1986.
5. Draper H. Euthanasia. In: Chadwick R, editor. Encyclopaedia of applied ethics, vol. 2. San Diego: Academic; 1998.