Perhaps you should try some spelling variations:
"chemical industry / waste optimization" » "chemical industry / rate optimization", "chemical industry / base optimization", "chemical industry / wash optimization"
"chemical industry / case optimization" » "chemical industry / base optimization", "chemical industry / cache optimization", "chemical industry / phase optimization"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"chemical industry / waste optimization\") OR (\"chemical industry / case optimization\"))".
• Removing quotes may allow a broader search: (( chemical industry / waste optimization ) OR ( chemical industry / case optimization )).
• Adding a wildcard symbol may retrieve word variants: (("chemical industry / waste optimization") OR ("chemical industry / case optimization"))*.