@article{JIS_2011__14_6_a0,
     author = {Pandey, Ram Krishna and Tripathi, Amitabha},
     title = {Note on a problem of {Motzkin} regarding density of integral sets with missing differences},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {14},
     number = {6},
     year = {2011},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2011__14_6_a0/}
}