Perhaps you should try some spelling variations:
"founded theory" » "grounded theory", "grounded theory6", "founding theory"
"blended theory" » "extended theory", "blending theory", "blended query"
"bands theory" » "band theory", "bang theory", "minds theory"

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: (("founded theory") OR ((("bands theory") OR ("blended theory")))).
• Removing quotes may allow a broader search: (( founded theory ) or ((( bands theory ) or ( blended theory )))).
• Adding a wildcard symbol may retrieve word variants: (("founded theory") or ((("bands theory") or ("blended theory"))))*.