1. D. Birkes, Orbits of linear algebraic groups, Annals of Mathematics 93(1971), 459–475.
2. A. Borel, Linear Algebraic Groups, Benjamin, New York, 1969.
3. A. Borel, Introduction aux groupes arithmetiques, Hermann, Paris, 1969.
4. A. Borel and Harish-Chandra, Arithmetic subgroups of algebraic groups, Annals of Mathematics 75(1962), 485–535.
5. S. Helgason, Differential Geometry and Symmetric Spaces, Academic Press, New York, 1962.