SILICON CARBIDE - World Health Organization
Fig. 1.2 Atomic stacking for silicon carbide polytypes The three most common polytypes in silicon carbide viewed in the  plane. From left to right: 4H-silicon carbide, 6H-silicon carbide, and 3C-silicon carbide; k and h denote crystal symmetry points that are cubic and hexagonal, respectively. From Kordina & Saddow (2006).