The former, which ends in 1147, is a work of learning and industry, but almost entirely based upon extant sources.

Many of his atlas' maps were based upon sources that no longer exist or are extremely rare.

Thomas did not disdain to draw upon Jewish philosophical sources.

Local authorities have always relied upon outside sources for many of the goods and services they require.

The play drew upon several contemporary sources for its inspiration.

Stage plays have drawn upon silent film styles and sources.

"I don't want to see us become totally dependent upon foreign sources for the technologies we need."

These reports were based upon anonymous "high level" sources and were both denied by the Administration.

His work often draws upon various sources in a process of cross-fertilization.

"They are dependent upon foreign sources for two-thirds of the newsprint utilized today," he said.