@article{10_37236_5610,
     author = {Christopher N. Swanson and Bill Correll, Jr. and Randy W. Ho},
     title = {Enumeration of parallelograms in permutation matrices for improved bounds on the density of {Costas} arrays},
     journal = {The electronic journal of combinatorics},
     year = {2016},
     volume = {23},
     number = {1},
     doi = {10.37236/5610},
     zbl = {1333.05016},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/5610/}
}