Perhaps you should try some spelling variations:
"international research/decision theory" » "international reserves/decision theory"
"operational research/decision theory" » "educational research/decision theory"

Try widening your search to All Fields.

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: (((("operational research/decision theory") OR ("international research/decision theory"))) OR ("operations research/decision theory")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"operational research/decision theory\") OR (\"international research/decision theory\"))) or (\"operations research/decision theory\"))".
• Removing quotes may allow a broader search: (((( operational research/decision theory ) OR ( international research/decision theory ))) or ( operations research/decision theory )).
• Adding a wildcard symbol may retrieve word variants: (((("operational research/decision theory") OR ("international research/decision theory"))) or ("operations research/decision theory"))*.