Rival, Ivan,Ewacha, Kevin.2009-03-232009-03-2319931993Source: Dissertation Abstracts International, Volume: 55-08, Section: B, page: 3344.9780315895935http://hdl.handle.net/10393/6484http://dx.doi.org/10.20381/ruor-11299Abstract Not Available.182 p.Mathematics.Thesis