The first of these terms can be written shortly as

- 1/4 ∂/∂_x__{σ} (F^{μν} F_{μν}),

and the second after differentiation can be transformed in the form

- ½ F^{μτ} F_{μν} _g_^{νρ} ∂_g__{στ}/∂_x__{σ}.