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Bibliography

[1]

K. Appel and F. Djorup, On the group generated by a free semigroup, Proc. Amer. Math. Soc. 15 (1964), 838-841. MR 0168682 (29:5940)

[2]

M. M. Day, Amenable semigroups, Illinois J. Math. 1 (1957), 509-544. MR 0092128 (19:1067c)

[3]

E. Følner, Note on groups with and without full Banach mean value, Math. Scand. 5 (1957), 5-11. MR 0094725 (20:1237)

[4]

A. H. Frey, Jr., Studies in amenable semigroups, Thesis, University of Washington, Seattle, Washington, 1960.

[5]

E. Granirer, Extremely amenable semigroups. II, Math. Scand. 20 (1967), 93-133. MR 0212551 (35:3422)

[6]

J. von Neumann, Zur allgemeinen Theorie des Masses, Fund. Math. 13 (1929), 73-116.

[7]

C. Wilde and K. Witz, Invariant means and the Stone-Čech compactification, Pacific J. Math. 21 (1967), 577-586. MR 0212552 (35:3423)