A.S. Rapinchuk, Algebraic and abstract simple groups: old and new (this survey was written in 2002 but was never published), article
P. Corvaja, J. Demeio, A. Rapinchuk, J. Ren, U. Zannier, Purely exponential parametrizations and their group-theoretic applications, arxiv.
A.S. Rapinchuk, W. Tralle, On almost strong approximation in reductive algebraic groups, arxiv.