@article{JGG_2001_5_1_a8,
     author = {C. Leopold and R. A. Gorska and S. A. Sorby},
     title = {International {Experiences} in {Developing} the {Spatial} {Visualization} {Abilities} of {Engineering} {Students}},
     journal = {Journal for geometry and graphics},
     pages = {081--092},
     publisher = {mathdoc},
     volume = {5},
     number = {1},
     year = {2001},
     url = {http://geodesic.mathdoc.fr/item/JGG_2001_5_1_a8/}
}