@article{10_4064_sm_44_1_1_15,
     author = {Charles Fefferman},
     title = {Estimates for double {Hilbert} transform},
     journal = {Studia Mathematica},
     pages = {1--15},
     year = {1972},
     volume = {44},
     number = {1},
     doi = {10.4064/sm-44-1-1-15},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-44-1-1-15/}
}