1. Easdown, D.,Biordered sets are biordered subsets of idempotents of semigroups,
2. Easdown, D.,A new proof that regular biordered sets come from regular semigroups,
3. Easdown, D.,Biordered sets of eventually regular semigroups,
4. Easdown, D. and T.E. Hall,Reconstructing some idempotent-generated semigroups from their biordered sets,
5. Nambooripad, K.S.S.,Structure of regular semigroups I, Memoirs Amer. Math. Soc. 22 (1979).