• Bulletin of the Korean Mathematical Society
• /
• v.21 no.1
• /
• pp.31-31
• /
• 1984

• Journal of the Korean Mathematical Society
• /
• v.32 no.3
• /
• pp.583-591
• /
• 1995

Unless otherwise stated, we always assume that X is a Banach space, and $1 < p, q < \infty with \frac{p}{1}+\frac{q}{1} = 1$. We use S(X) and B(X) to denote the unit sphere and the unit ball in X respectively.