  Integral equations for the spin-weighted spheroidal wave functions is given.
For the prolate spheroidal wave function with m=0, there exists the integral
equation whose kernel is(sin x)/x, and the sinc function kernel (sin x)/x is of
great mathematical significance. In the paper, we also extend the similar sinc
function kernel (sin x)/x to the case m and s both are not zero, which
interestingly turn out as some kind of Hankel transformation.
