(db:natbib+ocode:(F);srt2:1981;ocode:(HiB);ocode:(VBM)) ocode:(F) srt2:1981 ocode:(HiB) ocode:(VBM)db:natbib+ocode:(F);srt2:1981;ocode:(HiB);ocode:(VBM)libs:F_t1981libs:HiB_tlibs:VBM_t