1. On the efficiency of wreath products of groups;Ayık,2000
2. The semigroup efficiency of groups and monoids;Ayık;Math. Proc. Roy. Irish Acad.,2000
3. Minimal presentations and efficiency of semigroups;Ayık;Semigroup Forum,2000
4. On semigroup presentations and efficiency;Ayık;Semigroup Forum,2002
5. On defining groups efficiently without using inverses;Campbell;Math. Proc. Cambridge Philos. Soc.,2002