It adds that tighter controls on immigration could reduce the numbers of migrant workers from developing countries who are able to send money home - a substantial source of income for many Caribbean, Central American and South Asian countries.

BBC: Terrorism 'slows globalisation'

However, tackling the problem from a supply chain angle represents one of the best means of cutting off a very substantial source of income (tens of millions of dollars per year according to our estimates) from abusive armed groups.

FORBES: A Response to Global Witness

The reserve, located in the Texas panhandle, is the only long-term substantial storage source for helium in the world.

CNN: U.S. needs a strategy on helium

What they failed to mention is that the states have embraced the desire for individualism as a source of substantial income.

BBC: Flags on car plates - right or wrong?

Few authors who manage to find an agent and then a publisher or, lacking that, the funds to self-publish, find book sales a source of income substantial enough to provide for a single person, let alone two.

FORBES: When the Power of Financial Literacy Meets the Entrepreneurial Spirit

Private equity funds a substantial amount of new businesses and is the source of capital to rejuvenate failing businesses, which are major drivers of job growth in this economy.

FORBES: Private Equity Isn't About Greed; It's About Growth

Bank- loan funds, another source of relatively high yields, also enjoyed substantial net inflows in the year ending February 29, 2012, according to Morningstar.

FORBES: Are Your Bond Holdings Raising Your Portfolio's Risk Profile?

In fact, over the past three years Deutsche Bank has deliberately and dramatically reduced its dependence on risk-taking as a source of operating earnings, while enjoying more substantial progress with clients than at any time in its recent history.

ECONOMIST: Russia's rotten statelets

The principal source of the slowdown in economic growth that began last spring has been the substantial correction in the housing market.

NPR: Bernanke: U.S. Growth 'Moderate' as Inflation Rises