• Richard E. Block,
On the Mills–Seligman axioms for Lie algebras of classical type,
Transactions of the American Mathematical Society, 121 (1966), pp. 378–392. (The paper that gives the central extension defining the Virasoro algebra.) • Richard E. Block and Robert Lee Wilson, The Restricted Simple Lie Algebras are of Classical or Cartan Type,
Proceedings of the National Academy of Sciences of the United States of America August 15, 1984 vol. 81, no. 16, 5271–5274. ==References==