He has contributed to a number of news sources worldwide for 15 years.

Human activities have contributed to a number of the observed changes in climate.

He has also contributed to a number of short story collections.

She has also contributed to a number of films, radio programs, conferences.

He also contributed to a number of songs for films.

He also contributed articles to a large number of national and international journals.

He also contributed to a number of government committees on the health service and social policy.

He also contributed $114,300 to a number of Democratic campaigns in 2012.

Germans have contributed to a vast number of areas in American culture and technology.

He also contributed to a number of other Journals and publications.