现今历史学家写的书是间接来源。
Books written in the present day by historians are secondary sources.
生物质能是太阳能以化学能形式贮存在生物中的一种能量形式，直接或间接来源于植物的光合作用。
Biomass is solar energy to chemical energy stored in the form of a bio-energy in the form of, directly or indirectly from photosynthesis.
如果有监管，监管部门也会喜欢他们的，因为他们的原材料是直接或间接来源于产生于大气又终止于大气的二氧化碳。
If anything, regulation is likely to favour them because their raw material is, either directly or indirectly, carbon dioxide that has come from the atmosphere or would end up there.
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