Nonstandard Analysis in Topology: Nonstandard and Standard Compactifications. - S. Salbany; Todor Todorov (J. Symb. Log., 2000)

A non-Hausdorff quaternion multiplication. - Keith A. Hardie; S. Salbany; J. J. C. Vermeulen; Peter J. Witbooi (Theor. Comput. Sci., 2003)