@article{10_37236_2514,
     author = {Vadim E. Levit and Eugen Mandrescu},
     title = {A set and collection lemma},
     journal = {The electronic journal of combinatorics},
     year = {2014},
     volume = {21},
     number = {1},
     doi = {10.37236/2514},
     zbl = {1300.05230},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/2514/}
}