@article{10_4064_fm195_2_2,
     author = {Paul Gartside and Bojana Peji\'c},
     title = {The complexity of the set of squares in the
 homeomorphism group of the circle},
     journal = {Fundamenta Mathematicae},
     pages = {125--134},
     publisher = {mathdoc},
     volume = {195},
     number = {2},
     year = {2007},
     doi = {10.4064/fm195-2-2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm195-2-2/}
}