@article{10_4064_fm220_2_3,
     author = {D\'aniel T. Soukup and Paul J. Szeptycki},
     title = {The union of two $D$-spaces need not be $D$},
     journal = {Fundamenta Mathematicae},
     pages = {129--137},
     publisher = {mathdoc},
     volume = {220},
     number = {2},
     year = {2013},
     doi = {10.4064/fm220-2-3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm220-2-3/}
}