"Sumitomo" wa naze tsuyoi no ka
Subtitle: chō yūryō kigyō shūdan Sumitomo gurūpu no himitsu
By: Yūki Saburō.
Edition: Dai 1-han
Publisher: PHP Kenkyūjo
Published: 1985
Place of publication: Kyōto-shi
Language: jpn
Number of pages: 300
Subjects: Sumitomo Group.