Perhaps you should try some spelling variations:
"natural science series 1:, physics" » "natural sciences series 1:, physics", "natural science services 1:, physics", "natural science stories 1:, physics", "natural science theories 1:, physics", "natural science series 2:, physics"
"radio science series 3:, physics" » "radio science services 3:, physics", "radio science stories 3:, physics", "radio science theories 3:, physics"

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: (("natural science series 1:, physics") OR ("radio science series 3:, physics")).
• Removing quotes may allow a broader search: (( natural science series 1:, physics ) or ( radio science series 3:, physics )).
• Adding a wildcard symbol may retrieve word variants: (("natural science series 1:, physics") or ("radio science series 3:, physics"))*.