Perhaps you should try some spelling variations:
"linkage groups" » "linkage group", "link groups"
"life groups" » "lie groups", "life group", "line groups"
"like groups" » "lie groups", "large groups", "crime groups"
"disk groups" » "risk groups", "task groups", "risk group"

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: (((("life groups") OR ("like groups"))) OR ((("linkage groups") OR ("disk groups"))))*.
• Removing quotes may allow a broader search: (((( life groups ) or ( like groups ))) or ((( linkage groups ) or ( disk groups ))))*.