Income can also come from self - employment, a small business, unemployment checks, a pension, or hundreds of other primary sources. (bripblap.com)
What other primary source outside the planet provides its foundational heat? (hubpages.com)
The students were getting to read a wide variety of perspectives from both the left and right, civil liberties groups, the army field manual, and other primary sources about this topic. (edutopia.org)