1. P. Aizley, Structure theory for a class of convolution algebras, University Microfilms, Order #69-16,475, Ann Arbor, Michigan.
2. On a theorem of von Sterneck;Lehmer, D. H.;Bull. Amer. Math. Soc.,1931
3. Generating functions on idempotent semigroups with application to combinatorial analysis;Tainiter, M.;J. Combinatorial Theory,1968
4. Finite dimensional convolution algebras;Hewitt, Edwin;Acta Math.,1955