Garat, Alcides
Price, Richard, H., “Nonexistence of conformally flat slices of the Kerr spacetime”, Physical Review D (Particles, Fields, Gravitation, and Cosmology), 61:12 (2000), id.124011
Garat, Alcides, “Tetrads in geometrodynamics”, Journal of Mathematical Physics, 46:10 (2005), p.102502