We survey important developments in the theory of covering radius during the period 1985-1994. We present lower bounds, constructions and upper bounds, the linear and nonlinear cases, density and asymptotic results, normality, specific classes of codes, covering radius and dual distance, tables, and open problems.
Cohen, G. D.; Litsyn, S. N.; Lobstein, Antoine C.; and Mattson, H. F. Jr, "Covering Radius 1985-1994" (1994). Electrical Engineering and Computer Science - Technical Reports. 150.