The critical case
Hans Triebel · Birkhäuser Basel eBooks · 2001
By the terminology of (10.6) the critical case covers the spaces (13.1) $$ B_{pq}^{\frac{n} {p}} \left( {\mathbb{R}^n } \right) and F_{pq}^{\frac{n} {p}} \left( {\mathbb{R}^n } \right) with 0 < p < \infty and 0 < q \leqslant \infty . $$