Perhaps you should try some spelling variations:
"little groups" » "little group", "simple groups", "pile groups"
"life groups" » "lie groups", "like groups", "life group"
"line groups" » "lie groups", "like groups", "line 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 ((("little groups") OR ("line groups")))).
• Removing quotes may allow a broader search: (( life groups ) or ((( little groups ) or ( line groups )))).
• Adding a wildcard symbol may retrieve word variants: (("life groups") or ((("little groups") or ("line groups"))))*.