TY - JOUR A1 - Easterbrook, P.J. A1 - Gopalan, R. A1 - Berlin, J.A. A1 - Matthews, D.R. T1 - Publication bias in clinical research Y1 - 1991 DO - 10.1016/0140-6736(91)90201-Y VL - 337 IS - 8746 ER -