1. On stratifiable spaces;Borges, Carlos J. R.;Pacific J. Math.,1966
2. Some generalizations of metric spaces;Ceder, Jack G.;Pacific J. Math.,1961
3. H. Cook, Cartesian products and continuous semimetrics, Topology Conference at Arizona State University, Tempe, Ariz., 1967 (Editor: E. Grace).
4. A regular semi-metric space for which there is no semi-metric under which all spheres are open;Heath, Robert W.;Proc. Amer. Math. Soc.,1961
5. A paracompact semi-metric space which is not an 𝑀₃-space;Heath, R. W.;Proc. Amer. Math. Soc.,1966