1.   In addition, plants are the greatest single source of oxygen in the atmosphere.

2.   Suddenly revitalized and uncommonly clear-headed, he sensed that the cool water was the greatest source ofjoy he had ever known.

3.   Teachers believe that their interaction with pupils and the disciplinary problems which arise are the greatest source of stress in their work.

4.   The dust mite, which thrives in warm, moist air, is the greatest source of allergens for asthmatics.

5.   The greatest source of insecurity, as noted, lay in competition and the free and unpredictable movement of competitive Market prices.

6.   Unfortunately, the Crown Court which is the greatest source of the waste of public money is not being attacked.

7.   Historically, clinical evidence has been the greatest source of research into differences between the hemispheres.