Sorgente TeX:
\left. \begin{matrix} \text{8 corner }Cl^- \text{ions}= {8 \over 8} =1 Cl^- \text{per unit cell} \\ \text{6 face }Cl^- \text{ions}= {6 \over 2}= 3 Cl^- \text{per unit cell} \end{matrix} \right \} 4 Cl^-