I found on Wikipedia that the electromagnetic stress energy tensor in curved space-time with sign convention $(-, +, +, +)$ is
$$T_{\mu\nu} = -\frac{1}{\mu_0} \left ( F_{\mu \alpha} g^{\alpha \beta} F_{\beta \nu} - \frac{1}{4} g_{\mu \nu} F_{\sigma \alpha} g^{\alpha \beta} F_{\beta \rho} g^{\rho \sigma} \right ).$$
However, I need a reputable source for this equation. Does anyone know another source for this equation? All I could find was
$$T_{\mu\nu} = \frac{1}{\mu_{0}}( F^{\beta}{}_{\mu}F_{\beta\nu} - \frac{1}{4}g_{\mu\nu}F^{\alpha\beta}F_{\alpha\beta}).$$