Perhaps you should try some spelling variations:
"medical empirical review" » "media empirical review", "medicine empirical review", "medical empiricism review"
"medical ethical review" » "medical ethics review", "medicine ethical review", "medical surgical review", "medical technical review"
"medical clinical review" » "medical critical review"

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: (((("medical ethical review") OR ("medical clinical review"))) OR ("medical empirical review")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"medical ethical review\") OR (\"medical clinical review\"))) or (\"medical empirical review\"))".
• Removing quotes may allow a broader search: (((( medical ethical review ) OR ( medical clinical review ))) or ( medical empirical review )).
• Adding a wildcard symbol may retrieve word variants: (((("medical ethical review") OR ("medical clinical review"))) or ("medical empirical review"))*.