A good newspaper reporter takes advantage of what he learns from any source, even the "little bird told him so" type of source.

Solar energy seems to offer more hope than any other source of energy, particularly because those areas most in need of water lie rather close to the equator and have a relatively clear atmosphere.

Solar energy is a new source of energy.

He argues that the administration must look for alternative sources of revenue.

The administration cannot but look for alternative sources of revenue.

The world needs to develop new energy sources in place of oil.

The most likely sources of energy in hot and dry regions are the wind and the sun.

We must develop the renewable energy sources.

We must develop the renewable energy sources.

We must develop renewable energy sources.

The reporter refused to name his sources.

Another interesting source of energy is the heat that can be recovered from radioactive waste material.

This job is my bread and butter.

Gambling was by no means his only source of income.

Wind is a cheap and clean source of energy.

Mining is one of the main sources of wealth in Chile.