Constantin Nastasescu received his Ph. D. at the University of Bucharest in 1970 and became Prof. Titular in 1990. Since 1993 he is a member of the Roumanian Academy of Sciences. He published more than 125 scientific publications in international journals as well as several monographs and books. Fred Van Oystaeyen received his Ph. D. from the Free University of Amsterdam in 1972 and became professor at the University of Antwerp in 1975. He published over 225 papers and books and is coordinator of several European research programmes including the programme on noncommutative geometry (NOG) of the European Science Foundation and the project Liegrits of the EC in the 6th Framework Programme, as well as the educational programme on mathematical methods of robotics for ERASMUS.

• The Category of Graded Rings.- The Category of Graded Modules.- Modules over Stronly Graded Rings.- Graded Clifford Theory.- Internal Homogenization.- External Homogenization.- Smash Products.- Localization of Graded Rings.- Application to Gradability.- Appendix A: Some Category Theory.- Appendix B: Dimensions in an Abelian Category.- Bibliography.- Index.