The level of tetrachloroethylene in the well was considered low, however, and officials believe some other source, still unidentified, also contributed to the contamination.

At present, private sources contribute 45% of its annual funding.

But other sources, including those that might not be immediately obvious, contributed to the surplus.

Other countries and perhaps commercial sources may also contribute to the temporary loan, officials said.

Other sources such as galaxies and nebulae don't contribute significantly.

While Midwestern power plants are a major source, local sources contribute significantly.

Many sources contribute to levels of fine particle pollution and ozone that exceed national air quality standards.

Each source contributed to the attempt to understand what dementia sufferers needed in order to help them stay at home.

Traditional sources of revenue have lost their significance, and contribute more to the general confusion than to transparency.

A near hallucinatory source of illumination contributes further to the impact.