11.   If an unknown group was involved, several U.S. intelligence officials said, it would suggest that the nature of terrorism itself has been transformed.

12.   Instead of just putting out an album by an unknown group, it decided to introduce the band with a soundtrack first.

13.   Jethro Tull, an unknown group, made the cut, edging out another start-up band, Led Zeppelin.

14.   McCain objected to one television ad in particular that is being aired by a previously unknown group called Republicans for Clean Air.

15.   Scrushy is one of a largely unknown group of executives Gingrich has tapped for advice in crafting the Republican agenda.

16.   Several centuries ago some unknown group of white racists agreed that one drop of black blood made a person black.

17.   Some pinned suspicions on an unknown group looking for recognition.

18.   The agency said the leaflets praised Palestinian suicide bombings and were signed by a previously unknown group called Tanzim al-Fatah Afghanistan.

19.   The investigators were also analyzing a statement issued by a previously unknown Islamic group taking responsibility for the attack.

20.   The investigators were also analyzing the statement was a statement issued by a previously unknown Islamic group claiming responsibility for the attack.