The most detailed source covering the events of these years is historian Sebeos in his History of Heraclius.

The bibliometric studies involved the use of published and online bibliographic sources covering the literature published to the end of 1987.

It is the first reservoir of such information from the same consistent source covering most of the world.

The Al-Shifa factory was Sudan's primary source of pharmaceuticals, covering the majority of the Sudanese market.

This service aims to deliver world wide library and information services from main sources covering a broad range of academic fields, thus meeting the needs of the campus community.

The biographical sources covering the period are, unfortunately, not sufficiently detailed to permit a definite answer.

Groundwater is by far the main source of drinking water in Switzerland, covering 80% of requirements.

Little is known about this king due to the lack of sources covering this time.

Because written sources covering the era are scarce, Mindaugas' origins and family tree have not been conclusively established.

Diena was Latvia's main source of news during the Kremlin power struggle, covering events both in Moscow and at home.