@article{VM_2010_12_2_a0,
     author = {Paulus Gerdes},
     title = {Permutations and {Copi} mats, {Chidenguele,} {Mozambique}},
     journal = {Visual Mathematics},
     publisher = {mathdoc},
     volume = {12},
     number = {2},
     year = {2010},
     url = {http://geodesic.mathdoc.fr/item/VM_2010_12_2_a0/}
}