Perhaps you should try some spelling variations:
observational clinical » observation clinical, observations clinical, observational cinema
observational economy » observational astronomy, observational cohort, observational cinema
observational context » observational concepts, observational contacts, observation content
observational clues » observational aspects, observational results, observational techniques
observational case » observation case, observational basis, observational frame

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: ((((((((observational clinical) OR (observational case))) OR (observational economy))) OR (observational clues))) OR (observational context)).
• Adding a wildcard symbol may retrieve word variants: ((((((((observational clinical) or (observational case))) or (observational economy))) or (observational clues))) or (observational context))*.