Thermal plants are a significant secondary source of power.
"Parliament is only a secondary source of power," warns the economist Saeed Leylaz.
They fed Cairo's organic waste to the animals, whose meat provided a good secondary source of income.
The secondary source of supply, B, would in time also become depleted.
The crankcase is a secondary source of unburned hydrocarbons and, to a lesser extent, carbon monoxide.
We do see a lot of methadone getting diverted out here on the street from the clinic, and we have to watch our clients very carefully because it's a secondary source of income for a lot of them".
Still others, like the Goodman Equipment Corporation, a maker of small locomotives for mining and tunnel building, are shipping their main products in the old volumes, but feeling the slowdown in sales of spare parts, a secondary source of revenue.
Slowly, quietly, the mainstream media have become, for many involved in activism, politics and journalism itself, a secondary source of information, while social networks have become the primary source.
"This has always been seen in the past as a secondary source of revenue," said John Kennedy, chief executive of the International Federation of the Phonographic Industry, a London-based trade group for the major record labels.
The film historian Robert Sklar points out in his introduction that although local cinemas figure prominently in our national mythos, they actually were a secondary source of revenue for Hollywood.
Barely a decade after Pierre Omidyar founded eBay, more than seven hundred thousand Americans report it as their primary or secondary source of income, according to a study by the market-research firm AC Nielsen.
