1. Endomorphisms of minimal sets;Auslander, Joseph;Duke Math. J.,1963
2. American Mathematical Society Colloquium Publications, Vol. XXV;Birkhoff, Garrett,1961
3. On universal transformation groups;Chu, Hsin;Illinois J. Math.,1962
4. Variations on equicontinuity;Clay, Jesse Paul;Duke Math. J.,1963
5. A semigroup associated with a transformation group;Ellis, Robert;Trans. Amer. Math. Soc.,1960