\[\begin{pmatrix}j_{1}&j_{2}&j_{1}+j_{2}\\
m_{1}&m_{2}&-m_{1}-m_{2}\end{pmatrix}=(-1)^{j_{1}-j_{2}+m_{1}+m_{2}}\left(%
\frac{(2j_{1})!(2j_{2})!(j_{1}+j_{2}+m_{1}+m_{2})!(j_{1}+j_{2}-m_{1}-m_{2})!}{%
(2j_{1}+2j_{2}+1)!(j_{1}+m_{1})!(j_{1}-m_{1})!(j_{2}+m_{2})!(j_{2}-m_{2})!}%
\right)^{\frac{1}{2}},\]