Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{CMH_1961__36_139236, author = {I.I, Jr. Hirschman}, title = {Variation {Diminishing} {Transformations} and {STURM-LIOUVILLE} {Systems.}}, journal = {Commentarii mathematici Helvetici}, pages = {214--233}, publisher = {mathdoc}, volume = {36}, year = {1961}, zbl = {0109.05804}, url = {http://geodesic.mathdoc.fr/item/CMH_1961__36_139236/} }
I.I, Jr. Hirschman. Variation Diminishing Transformations and STURM-LIOUVILLE Systems.. Commentarii mathematici Helvetici, Tome 36 (1961), pp. 214-233. http://geodesic.mathdoc.fr/item/CMH_1961__36_139236/