@article{10_4064_cm117_1_2,
     author = {A. M. Aghdam and A. Najafizadeh},
     title = {Square subgroups of rank two abelian groups},
     journal = {Colloquium Mathematicum},
     pages = {19--28},
     publisher = {mathdoc},
     volume = {117},
     number = {1},
     year = {2009},
     doi = {10.4064/cm117-1-2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm117-1-2/}
}