TY - JOUR T1 - Variation in selection pressures on the goldenrod gall fly and the competitive interactions of its natural enemies JF - Oecologia Y1 - 1989 A1 - Abrahamson,W.G. A1 - Sattler,J.F. A1 - McCrea,K.D. A1 - Weis,A.E. SP - 15 EP - 22 VL - 79 ER -