  In his classical paper [5], Koornwinder studied a family of orthogonal
polynomials of two variables, derived from symmetric polynomials. This family
possesses a rare property that orthogonal polynomials of degree $n$ have
$n(n+1)/2$ real common zeros, which leads to important examples in the theory
of minimal cubature rules. This paper aims to give an account of the minimal
cubature rules of two variables and examples originating from Koornwinder
polynomials, and we will also provide further examples.
