Equality in Pollard's theorem on set addition of congruence classes E. Nazarewicz; M. O'Brien; M. O'Neill; C. Staples — 2007 Acta Arithmetica
On characteristic identities for Lie algebras D. M. O'Brien; A. Cant; A. L. Carey — 1977 Annales de l'I.H.P. Physique théorique