Hughston, L P and Sommers, P. 1973. The Symmetries of Kerr Black Holes. Communications in Mathematical Physics, 33(2), pp. 129-133. ISSN 0010-3616 [Article]

Hughston, L P and Sommers, P. 1973. Spacetimes with Killing Tensors. Communications in Mathematical Physics, 32(2), pp. 147-152. ISSN 0010-3616 [Article]

Hughston, L P; Penrose, R; Sommers, P and Walker, M. 1972. On a Quadratic First Integral for the Charged Particle Orbits in the Charged Kerr Solution. Communications in Mathematical Physics, 27(4), pp. 303-308. ISSN 0010-3616 [Article]