1. Artin, E., Geometric Algebra, Wiley Interscience, New York, 1957.
2. Bak, A., The stable structure of quadratic modules, Thesis, Columbia University, 1969.
3. Lecture Notes in Math.;H. Bass,1973
4. Cao Chongguang and Wang Luqun, Normal subgroups of symplectic groups over rings with one in its stable range (in Chinese),Acta Math. Sinica,29 (1986), 323–326.
5. Dieudonné, J., La Geometrie des Groupes Classiques, 3rd ed., Springer-Verlag, Berlin-New York, 1971.