Perhaps you should try some spelling variations:
"nato science theory c:, mathematical and medical sciences" » "national science theory c:, mathematical and medical sciences"
"nato science theory c:, mathematical and social sciences" » "national science theory c:, mathematical and social sciences"

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: (((("nato science theory c:, mathematical and medical sciences") OR ("nato science theory c:, mathematical and social sciences"))) OR ("radio science theory c:, mathematical and physical sciences")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"nato science theory c:, mathematical and medical sciences\") OR (\"nato science theory c:, mathematical and social sciences\"))) or (\"radio science theory c:, mathematical and physical sciences\"))".
• Removing quotes may allow a broader search: (((( nato science theory c:, mathematical and medical sciences ) OR ( nato science theory c:, mathematical and social sciences ))) or ( radio science theory c:, mathematical and physical sciences )).
• Adding a wildcard symbol may retrieve word variants: (((("nato science theory c:, mathematical and medical sciences") OR ("nato science theory c:, mathematical and social sciences"))) or ("radio science theory c:, mathematical and physical sciences"))*.