@article{10_4153_CJM_1974_067_0,
     author = {Ruckle, William H.},
     title = {On the {Classification} of {Biorthogonal} {Sequences}},
     journal = {Canadian journal of mathematics},
     pages = {721--733},
     year = {1974},
     volume = {26},
     number = {3},
     doi = {10.4153/CJM-1974-067-0},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1974-067-0/}
}