C2 N−1 m−2\mathrm{C}^{2} \mathrm{~N}^{-1} \mathrm{~m}^{-2}C2 N−1 m−2
NA−2NA^{-2}NA−2
Nm2C−2\mathrm{Nm}^{2} \mathrm{C}^{-2}Nm2C−2
Am−2\mathrm{Am}^{-2}Am−2
