@article{EXMA_2003__12_4_51272,
     author = {Havas, George and Robertson, Edmund F.},
     title = {Irreducible cyclic presentations of the trivial group.},
     journal = {Experimental mathematics},
     pages = {487--490},
     publisher = {mathdoc},
     volume = {12},
     number = {4},
     year = {2003},
     zbl = {1062.20036},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EXMA_2003__12_4_51272/}
}