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