Perhaps you should try some spelling variations:
"nato science theories b:, physics" » "nato science three b:, physics", "radio science theories b:, physics", "nato science theories 3:, physics", "nato science theories 4:, physics", "nato science theories 1:, physics"
"national science theory b:, physics" » "natural science theory b:, physics", "spatial science theory b:, physics", "animal science theory b:, physics"
"nato science theory b:, physics" » "radio science theory b:, physics"

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 theories b:, physics") OR ((("nato science theory b:, physics") OR ("national science theory b:, physics")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"nato science theories b:, physics\") or (((\"nato science theory b:, physics\") OR (\"national science theory b:, physics\"))))".
• Removing quotes may allow a broader search: (( nato science theories b:, physics ) or ((( nato science theory b:, physics ) OR ( national science theory b:, physics )))).
• Adding a wildcard symbol may retrieve word variants: (("nato science theories b:, physics") or ((("nato science theory b:, physics") OR ("national science theory b:, physics"))))*.