Perhaps you should try some spelling variations:
"nato science theories a:, life sciences" » "nato science three a:, life sciences", "radio science theories a:, life sciences"
"national science theories a:, life sciences" » "national science three a:, life sciences", "spatial science theories a:, life sciences", "animal science theories a:, life sciences", "natural sciences theories a:, life sciences"
"natural science theories a:, life sciences" » "natural science three a:, life sciences", "natural sciences theories a:, life sciences"
"nato science theory a:, life sciences" » "radio science theory a:, life sciences"

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• If you are trying to use Boolean operators, they must be ALL CAPS: (((("nato science theories a:, life sciences") OR ("nato science theory a:, life sciences"))) OR ((("national science theories a:, life sciences") OR ("natural science theories a:, life sciences")))).
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• Adding a wildcard symbol may retrieve word variants: (((("nato science theories a:, life sciences") OR ("nato science theory a:, life sciences"))) or ((("national science theories a:, life sciences") or ("natural science theories a:, life sciences"))))*.