@article{10_2307_120971,
     author = {Michael Lacey and Christoph Thiele},
     title = {On {Calder\'on's} conjecture},
     journal = {Annals of mathematics},
     year = {1999},
     volume = {149},
     number = {2},
     doi = {10.2307/120971},
     zbl = {0934.42012},
     url = {http://geodesic.mathdoc.fr/articles/10.2307/120971/}
}