\partial^{γ \dot{γ}} \partial_{γ \dot{γ}} ϕ_{α_{1} . . . α_{k} {\dot{β}}_{1} . . . {\dot{β}}_{n}}^{(k, n)} = 2 e^{2} m^{2} x^{α_{k + 1} {\dot{β}}_{n + 1}} x^{α_{k + 2} {\dot{β}}_{n + 2}} ϕ_{α_{1} . . . α_{k} α_{k + 1} α_{k + 2} {\dot{β}}_{1} . . . {\dot{β}}_{n} {\dot{β}}_{n + 1} {\dot{β}}_{n + 2}}^{(k + 2, n + 2)}