1. Real commutative semigroups on the plane;Horne, J. G., Jr.;Pacific J. Math.,1961
2. One-parameter subgroups in semigroups in the plane;Horne, J. G., Jr.;Michigan Math. J.,1962
3. Semigroups on a half-plane;Horne, J. G., Jr.;Trans. Amer. Math. Soc.,1962
4. The boundary of a one-parameter group in a semigroup;Horne, J. G., Jr.;Duke Math. J.,1964
5. A locally compact connected group acting on the plane has a closed orbit;Horne, J. G., Jr.;Illinois J. Math.,1965