TY - JOUR AU - Kessner, D M; Kalk, C E; Singer, J TI - Assessing health quality-the case for tracers JO - N Engl J Med VL - 288 PY - 1973 DO - 10.1056/NEJM197301252880406 L3 - PubMed-ID: 4682231 SP - 189 EP - 194 ER -