Journal of Mathematical Physics
All tensors of contravariant rank two which are divergence‐free on one index, concomitants of a spinor field σiAX′ together with its first two partial derivatives, and scalars under spin transformations are constructed. The Einstein and metric tensors are the only candidates.
A Characterization of the Einstein Tensor in Terms of Spinors (with D. Lovelock), J. Math. Phys. 17 (1976), 1001–1003.