@article{10_4153_CMB_1974_072_2,
     author = {Spoar, G. and Lane, N. D.},
     title = {On {Singular} {Points} of {Normal} {Arcs} of {Cyclic} {Order} {Four}},
     journal = {Canadian mathematical bulletin},
     pages = {391--396},
     year = {1974},
     volume = {17},
     number = {3},
     doi = {10.4153/CMB-1974-072-2},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1974-072-2/}
}