Perhaps you should try some spelling variations:
"nato science overview b:, physics" » "nato science review b:, physics", "nato service overview b:, physics", "nato change overview b:, physics", "radio science overview b:, physics", "national science overview b:, physics", "nato science overview 1:, physics", "nato science overview 1.1:, physics", "nato science overview 1.2:, physics"
"nato science service b:, physics" » "radio science service b:, physics", "national science service b:, physics", "nato science service bus:, physics", "nato science service big:, physics", "nato science service bei:, physics"
"nato science service bi:, physics" » "radio science service bi:, physics", "national science service bi:, physics", "nato science service bus:, physics", "nato science service busi:, physics", "nato science service bigi:, physics", "nato science service beii:, physics"
"nato science service bigi:, physics" » "radio science service bigi:, physics", "national science service bigi:, physics", "nato science service big:, physics", "nato science services big:, physics", "nato science service bei:, physics", "nato science service busgi:, physics", "nato science service busigi:, physics", "nato science service bigigi:, physics", "nato science service beiigi:, physics"

Try widening your search to All Fields.

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• If you are trying to use Boolean operators, they must be ALL CAPS: (("nato science overview b:, physics") OR ((("nato science service b:, physics") OR ((("nato science service bi:, physics") OR ("nato science service bigi:, physics")))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"nato science overview b:, physics\") or (((\"nato science service b:, physics\") or (((\"nato science service bi:, physics\") OR (\"nato science service bigi:, physics\"))))))".
• Removing quotes may allow a broader search: (( nato science overview b:, physics ) or ((( nato science service b:, physics ) or ((( nato science service bi:, physics ) OR ( nato science service bigi:, physics )))))).
• Adding a wildcard symbol may retrieve word variants: (("nato science overview b:, physics") or ((("nato science service b:, physics") or ((("nato science service bi:, physics") OR ("nato science service bigi:, physics"))))))*.