スレーター積分
∫ Y l m Y l ′ m ′ Y L − M d 2 Ω = ( − 1 ) m + m ′ A ^ L ( l , m , l ′ , m ′ ) = ( − 1 ) m c L ( l , − m , l ′ , m ′ ) . {\displaystyle \int Y_{\ell }^{m}Y_{\ell '}^{m'}Y_{L}^{-M}d^{2}\Omega =(-1)^{m+m'}{\hat {A}}^{L}(\ell ,m,\ell ',m')=(-1)^{m}c^{L}(\ell ,-m,\ell ',m').}
Y l m Y l ′ m ′ = ∑ l ′′ ( − 1 ) m ′ c l ′′ ( l , − m , l ′ , m ′ , ) Y l ′′ m + m ′ , {\displaystyle Y_{\ell }^{m}Y_{\ell '}^{m'}=\sum _{\ell ''}(-1)^{m'}c^{\ell ''}(\ell ,-m,\ell ',m',)Y_{\ell ''}^{m+m'},}