General Relativity: An Introduction for Physicists · Problem 8.10
The gravitational field equations — Hobson, Efstathiou & Lasenby
Physics · general-gravitational-field-equations
Problem
Find the most general tensor which can be constructed from the curvature tensor and the metric tensor and which contains terms no higher than quadratic in the second-order derivatives of gμν. Hence write down the most general form of the gravitational field equations in such a theory.