Perhaps you should try some spelling variations:
"nato science theory c:, mathematical and physical sciences" » "nato science theory c:, mathematical and medical sciences"
"national science theory c:, mathematical and physical sciences" » "national science theory c:, mathematical and medical sciences", "natural science theory c:, mathematical and physical sciences", "spatial science theory c:, mathematical and physical sciences", "animal science theory c:, mathematical and physical sciences"
"radio science theory c:, mathematical and physical sciences" » "radio science theory c:, mathematical and medical 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 physical sciences") OR ("national science theory c:, mathematical and physical 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 physical sciences\") OR (\"national science theory c:, mathematical and physical sciences\"))) or (\"radio science theory c:, mathematical and physical sciences\"))".
• Removing quotes may allow a broader search: (((( nato science theory c:, mathematical and physical sciences ) OR ( national science theory c:, mathematical and physical sciences ))) or ( radio science theory c:, mathematical and physical sciences )).
• Adding a wildcard symbol may retrieve word variants: (((("nato science theory c:, mathematical and physical sciences") OR ("national science theory c:, mathematical and physical sciences"))) or ("radio science theory c:, mathematical and physical sciences"))*.