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3. Kac, V.: Simple irreducible graded Lie algebras of finite growth (in Russian). Izv. Akad. Nauk SSSR32, 1323–1367 (1968); English translation: Math. USSR-Izv.2, 1271–1311 (1968)
4. Kac, V.: Infinite-dimensional Lie algebras and Dedekind's η-function (in Russian). Funkt. Anal. Ego Prilozheniya8, 77–78 (1974); English translation: Funct. Anal. Appl.8, 68–70 (1974)
5. Kac, V.: Infinite-dimensional algebras, Dedekind's η-function, classical Möbius function, and the very strange formula. Advan. Math. (to appear)