Set Difference of Cartesian Products

Theorem
$$\left({S_1 \times S_2}\right) - \left({T_1 \times T_2}\right) = \left({S_1 \times \left({S_2 - T_2}\right)}\right) \cup \left({\left({S_1 - T_1}\right) \times S_2}\right)$$