@article{DCG_1994__11_3_131300,
     author = {Pavel Valtr},
     title = {Unit {Squares} {Intersecting} {All} {Secants} of a {Square.}},
     journal = {Discrete & computational geometry},
     pages = {235--240},
     publisher = {mathdoc},
     volume = {11},
     number = {3},
     year = {1994},
     zbl = {0799.52015},
     url = {http://geodesic.mathdoc.fr/item/DCG_1994__11_3_131300/}
}