Since my area are algebraic graded structures, I need help in the field of modular theory !
Concerning the graded structures, especially graded rings (in Krasner sense) I recommend scientific paper:
1. M. Krasner: Anneaux graduees generaux (Colloque d’Algebre Rennes, Rennes,1980, pp. 209-308,
and my commun scientific monograph with Marc Krasner
2. M. Krasner, M. Vukovic: Strucures paragraduees (groups, rings, modules) Queen’s papers in Pure and Applied Mathematics, No 77, Queen’s University, Kingston Ontario, Canada, 1987, pp. 163.