1. [Be] G. M. Bergman, A note on growth functions of algebras and semigroups, mimeographed notes, University of California, Berkeley, 1978.
2. Über die Gelfand-Kirillov-Dimension;Borho, Walter;Math. Ann.,1976
3. Sur les corps liés aux algèbres enveloppantes des algèbres de Lie;Gelfand, I. M.;Inst. Hautes \'{E}tudes Sci. Publ. Math.,1966
4. Research Notes in Mathematics;Krause, G. R.,1985
5. On the transcendence degree of group algebras of nilpotent groups;Lorenz, Martin;Glasgow Math. J.,1984