The SIGMA Project and Database Issues. - Noboru Akima (IEEE Data Eng. Bull., 1987)

Industrializing Software Development: A Japanese Approach. - Noboru Akima; Fusatake Ooi (IEEE Softw., 1989)

Sigma system: Concepts and structure. - Noboru Akima; Shuji Nakata; Akiyoshi Nishijima; Tetsuya Kubo; Yasuo Konishi (Future Gener. Comput. Syst., 1992)