1. Editorial. Vital decision;BMJ,1967
2. Clinical problem solving: too old for what?;Thibault;N Engl J Med,1993
3. Occasional notes: you're never too old;Wong;N Engl J Med,1993
4. Setting limits;Callahan,1987
5. Age as a criterion for rationing health care;Levinsky;N Engl J Med,1990