@article{10_4064_ap_48_2_167_173,
     author = {A. K. Layek},
     title = {Directional qualitative cluster sets},
     journal = {Annales Polonici Mathematici},
     pages = {167--173},
     publisher = {mathdoc},
     volume = {48},
     number = {2},
     year = {1988},
     doi = {10.4064/ap-48-2-167-173},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-48-2-167-173/}
}