TY  - BOOK
AU  - Nastasescu Constantin
AU  - Oystaeyen Freddy Van
TI  - Methods of graded rings
SN  - 3-540-20746-5
U1  - 512.55 
PY  - 2004///
CY  - Berlin
PB  - Springer-Verlag
KW  - Hopf algebra
ER  -