The first involves sheep. Researchers have found that hair sheep are a good source of blood for use in tests to diagnose infectious diseases in people.

VOA: special.2009.08.03

His excuses became a continuing source of trouble for President Lincoln.

VOA: special.2009.09.03

And alfalfa can be a valuable food source for animals.

VOA: special.2010.02.09

Using non-performing rubber trees as a source of power also helps rejuvenate rubber production by making room for new planting.

VOA: standard.2009.09.13

U.S.drug officials say Mexico is either the source or a transshipment route for most of the illegal drugs that enter the United States.

VOA: standard.2009.03.25

(Speaking) Institute director Eric Leonhardt says he's had his eye on the dairy herd as a source of transportation fuel for a long time.

VOA: standard.2010.02.23

For many investors in Asia, gold's role as a source of safety and value has been reinforced over the past year of economic uncertainty.

VOA: standard.2010.07.21

The camp has become a source of tension among Calais residents and in France's relations with Britain, with London pushing for tighter border control.

VOA: standard.2009.09.22

Cigarette taxes are a vital revenue source for New York State, which has the highest-priced cigarettes in the nation - almost $15 a pack.

VOA: standard.2010.08.11

The shutdown is bad news for the recession-hit country partly because it will lose a source of cheap electricity and be forced to import more expensive energy.

VOA: standard.2010.01.01

A source of anger for many lawmakers at the hearing was a U.S.government contract for a so-called "virtual fence" monitoring system along the nearly 3200-kilometer U.S.-Mexico border.

VOA: standard.2010.04.21

The vast reddish desert that covers much of Somalia's central Mudug region has always been a source of wealth, as well as calamity, for thousands of pastoral families.

VOA: standard.2009.10.06

The United Nations Security Council later imposed sanctions on Pyongyang, which have impeded its efforts to sell conventional weapons abroad, a major source of income for the cash-strapped nation.

VOA: standard.2009.12.08

The bonuses and other seemingly corporate excesses are a source of frustration for the Obama administration as it seeks to rescue financial firms while maintaining public support for these efforts.

VOA: standard.2009.03.15