The SBML file to accompany the example given in the paper "A critical examination of stoichiometric and path-finding approaches to metabolic pathways" by F.J. Planes and J.E. Beasley can be found here.
To access that file do right-click and Save Target As. This is because opening that file directly in Internet Explorer is not recommended as that adds hyphens to the file.
J E Beasley