1. A. A. Balinskii and S. P. Novikov, ?Poisson brackets of hydrodynamic type, Frobenius algebras, and Lie algebras,? Dokl. Akad. Nauk SSSR,283, No. 5, 1036?1039 (1985).
2. S. P. Novikov, ?The geometry of conservative systems of hydrodynamic type. The method of averaging for field-theoretical systems,? Usp. Mat. Nauk,40, No. A, 79?89 (1985).
3. R. Amayo and I. Stewart, Infinite-dimensional Lie Algebras, Noordhoof Int'l. Publ., Leyden (1974).