@article{10_4064_sm_49_3_217_223,
     author = {Luis Caffarelli and Calixto Calder\'on},
     title = {Weak type estimates for the {Hardy-Littlewood} maximal functions},
     journal = {Studia Mathematica},
     pages = {217--223},
     publisher = {mathdoc},
     volume = {49},
     number = {3},
     year = {1973},
     doi = {10.4064/sm-49-3-217-223},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-49-3-217-223/}
}