@article{10_4153_CMB_1977_077_5,
     author = {Gardner, B.},
     title = {A {Note} on (r, {\ensuremath{\lambda})-Systems}},
     journal = {Canadian mathematical bulletin},
     pages = {511--512},
     year = {1977},
     volume = {20},
     number = {4},
     doi = {10.4153/CMB-1977-077-5},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1977-077-5/}
}