1. http://www.math.mcgill.ca/labute/courses/133f03/VectorHistory.html
2. http://www.britannica.com/topic/vector-mathematics
3. http://mathinsight.org/vector_introduction
4. https://www.khanacademy.org/math/linear-algebra/vectors_and_spaces/
5. https://en.wikipedia.org/wiki/Linear_independence