@article{10_4064_fm_65_2_227_242,
     author = {Artur Rubin and Jean Rubin},
     title = {Extended operations and relations on the class of ordinal numbers},
     journal = {Fundamenta Mathematicae},
     pages = {227--242},
     publisher = {mathdoc},
     volume = {65},
     number = {2},
     year = {1969},
     doi = {10.4064/fm-65-2-227-242},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-65-2-227-242/}
}