@article{10_4153_CMB_1972_067_1,
     author = {Holub, J. R. and Retherford, J. R.},
     title = {A {Note} on {Unconditional} {Bases}},
     journal = {Canadian mathematical bulletin},
     pages = {369--372},
     year = {1972},
     volume = {15},
     number = {3},
     doi = {10.4153/CMB-1972-067-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1972-067-1/}
}