\[\sum_{j_{3}m_{3}}(2j_{3}+1)\begin{pmatrix}j_{1}&j_{2}&j_{3}\\
m_{1}&m_{2}&m_{3}\end{pmatrix}\begin{pmatrix}j_{1}&j_{2}&j_{3}\\
m^{\prime}_{1}&m^{\prime}_{2}&m_{3}\end{pmatrix}=\delta_{m_{1},m^{\prime}_{1}}%
\delta_{m_{2},m^{\prime}_{2}},\]