\[\frac{1}{2\pi}\int_{0}^{\pi}H_{n}\left(\cos\theta\,|\,q\right)H_{m}\left(\cos%
\theta\,|\,q\right){\left|\left({\mathrm{e}}^{2\mathrm{i}\theta};q\right)_{%
\infty}\right|}^{2}\,\mathrm{d}\theta=\frac{\delta_{n,m}}{\left(q^{n+1};q%
\right)_{\infty}}.\]