1.   Agriculture, deforestation and the other secondary sources of greenhouse gases are critical to many.

2.   In his failure to take these differences into account, Leibniz fell victim to his reliance on secondary sources.

3.   Scholars and researchers use the library approach when attempting to write articles for publication based on secondary sources.

4.   The book is based mainly on primary sources rather than secondary sources.

5.   These books also give secondary sources, and historians views on the subject.

6.   Tens of millions of reprint requests are mailed each year, the authors having identified the existence of the papers from secondary sources.

7.   In the main they relied upon their own convictions and inspirations and on secondary sources of various kinds.

8.   These are required for obtaining, checking and retrieving specific facts and pieces of information, particularly but not entirely from secondary sources...

9.   Secondary sources, in contrast, are interpretations of the past produced at a later date.