訂正日: 2006/08/29訂正理由: -訂正箇所: 引用文献情報訂正内容: Right : 1) E. Hopf: Fuchsian groups and ergodic theory. Trans. Amer. Math. Soc. 39 (1936). Ergodentheorie. Berlin (1937). 2) M. Tsuji: On Hopf's ergodic theorem. Proc. Imp. Acad. (1944). Jap. Journ, Math. 19 (1945). 3) M. Tsuji, 1.c. 2) 4) Siegel: Some remarks on discontinuous groups. Ann. Math. 46 (1945). M. Tsuji: Theory of Fuchsian groups. Jap. Journ. Math. 21 (1951).