@article{10_4064_sm_99_3_199_220,
     author = {Sergio Segura de Le\'on},
     title = {Bukhvalov type characterizations of {Urysohn} operators},
     journal = {Studia Mathematica},
     pages = {199--220},
     year = {1991},
     volume = {99},
     number = {3},
     doi = {10.4064/sm-99-3-199-220},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-99-3-199-220/}
}