\(| J M j_1 j_2 \rangle = \hspace{1mm}\) \(\sum\limits C \ | j_1 j_2 m_1 m_2 \rangle\)
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\(| j_1 j_2 m_1 m_2 \rangle = \hspace{1mm}\) \(\sum\limits C \ | J M j_1 j_2 \rangle\)