@article{MS2_1983__53_166863,
     author = {Erling Folner},
     title = {Some special {W-almost} periodic sets on the integers.},
     journal = {Mathematica Scandinavica},
     pages = {185--192},
     publisher = {mathdoc},
     volume = {53},
     year = {1983},
     zbl = {0517.43005},
     url = {http://geodesic.mathdoc.fr/item/MS2_1983__53_166863/}
}