Perhaps you should try some spelling variations:
"linkage groups" » "linkage group", "link groups"
"elite groups" » "like groups", "line groups", "finite groups"
"life groups" » "like groups", "life group", "line groups"
"lie groups" » "like groups", "live groups", "line groups"

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: (("elite groups") OR ((("linkage groups") OR ((("lie groups") OR ("life groups")))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"elite groups\") or (((\"linkage groups\") or (((\"lie groups\") OR (\"life groups\"))))))".
• Removing quotes may allow a broader search: (( elite groups ) or ((( linkage groups ) or ((( lie groups ) OR ( life groups )))))).
• Adding a wildcard symbol may retrieve word variants: (("elite groups") or ((("linkage groups") or ((("lie groups") OR ("life groups"))))))*.