1. Ahmad, A.G.B.: The application of pictures to decision problems and relative presentations. Ph.D. thesis, University of Glasgow (1995)
2. Ahmad, A.G.B., Al-Mulla, M.A., Edjvet, M.: Asphericity of length four relative group presentations. J. Algebra. Appl. (to appear)
3. Aldwaik, S., Edjvet, M.: On the asphericity of a family of positive relative group presentations. Edinb. Math. Soc. (to appear)
4. Anshel, M., Prener, R.: On free products of finite Abelian groups. Proc. Am. Math. Soc. 34, 343–345 (1972). doi: 10.2307/2038369
5. Babai, L., Goodman, A., Kantor, W., Luks, E., Palfy, P.: Short presentations for finite groups. J. Algebra 194(1), 79–112 (1997). doi: 10.1006/jabr.1996.6980