References
- Glokhehn , H. 1963 . Arch. Rationd Mech. Anal,, . 14 : 384 – 404 .
- Lu , J. 1988 . J. Math. Res. & Expositin . 03 : 419 – 425 .
- Sather , D. 1966 . Pacific J. of Math., . 19 ( 1 ) : 147 – 157 .
- Weinberge , H.F. 1956 . Ann. of Math., . 64 : 505 – 513 .