What is the primary source of mercury pollution?
Livestock ranching is the primary source of agricultural income.
This is the primary source of income for myself and my [four] workers," he says.
Football is the primary source of income for most athletic departments.
Seafood is the primary source of protein for many people around the world.
When money is the primary source of power, the special interests win hands down.
The British Association of Medical Microbiologists has reported that Spain is the primary source of legionella infection in returning tourists.
Solar ultraviolet radiation, which dissociates molecules of water vapour, methane, and hydrogen, is the primary source of atomic hydrogen.
The runoff from valley irrigation is the primary source for the sea, and negotiators from California water districts have been directed to protect the sea.
They were not because of extensive problems with the system, which is the primary source of voter information for the major news organizations.
Azerbaijan is the primary source of oil for a pipeline running from the capital, Baku, to a port on the Turkish Mediterranean.
