Perhaps you should try some spelling variations:
"underground workings" » "underground openings", "underground mining", "underground wireless"
"underground parking" » "underground banking", "underground mining", "underground openings"
"underground parts" » "underground gas", "underground press", "underground karst"
"underground works" » "underground coal", "underground water", "underground gas"

Try widening your search to All Fields.

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: (((("underground parking") OR ("underground parts"))) OR ((("underground workings") OR ("underground works")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"underground parking\") or (\"underground parts\"))) or (((\"underground workings\") OR (\"underground works\"))))".
• Removing quotes may allow a broader search: (((( underground parking ) or ( underground parts ))) or ((( underground workings ) OR ( underground works )))).
• Adding a wildcard symbol may retrieve word variants: (((("underground parking") or ("underground parts"))) or ((("underground workings") OR ("underground works"))))*.