Perhaps you should try some spelling variations:
"grounded theory6" » "grounded theorie", "grounded theory8.1", "grounded theories"
"founded theory" » "founding theory", "founded where", "sound theory"
"coupled theory" » "coupling theory", "coupled thermo", "coupled memory"

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: (("grounded theory") OR ((((("founded theory") OR ("grounded theory6"))) OR ("coupled theory")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"grounded theory\") or (((((\"founded theory\") OR (\"grounded theory6\"))) or (\"coupled theory\"))))".
• Removing quotes may allow a broader search: (( grounded theory ) or ((((( founded theory ) OR ( grounded theory6 ))) or ( coupled theory )))).
• Adding a wildcard symbol may retrieve word variants: (("grounded theory") or ((((("founded theory") OR ("grounded theory6"))) or ("coupled theory"))))*.