Perhaps you should try some spelling variations:
economics experiments » economic experiments, proteomics experiments, dynamics experiments
boarding papers » boarding pass, boarding passes, marking papers
working papers » working paper

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: oecd ((economics experiments) OR (economics management)) ((boarding papers) OR (working papers)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "oecd ((economics experiments) or (economics management)) ((boarding papers) OR (working papers))".
• Adding a wildcard symbol may retrieve word variants: oecd ((economics experiments) or (economics management)) ((boarding papers) OR (working papers))*.