@article{1138036120, author = {Nickel, Paul A.}, title = {A biharmonic normal operator}, journal = {Kodai Math. J.}, volume = {3}, number = {1}, year = {1980}, pages = { 59-69}, language = {en}, url = {http://dml.mathdoc.fr/item/1138036120} }
Nickel, Paul A. A biharmonic normal operator. Kodai Math. J., Tome 3 (1980) no. 1, pp. 59-69. http://gdmltest.u-ga.fr/item/1138036120/