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.
