Perhaps you should try some spelling variations:
green chromatography » gel chromatography, protein chromatography, current chromatography
ion chromatography » gas chromatography, column chromatography, liquid chromatography
_ chromatography » gas chromatography, layer chromatography
link green » think green, link free, link tree

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: (( link green chromatography ) OR ( think ((ion chromatography) OR (_ chromatography)) )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( link green chromatography ) or ( think ((ion chromatography) OR (_ chromatography)) ))".
• Adding a wildcard symbol may retrieve word variants: (( link green chromatography ) or ( think ((ion chromatography) OR (_ chromatography)) ))*.