@article{BUMI_1963_3_18_3_219_0, author = {Richard Bellman}, title = {On the nonnegativity of Green's functions.}, journal = {Bollettino dell'Unione Matematica Italiana}, volume = {18}, year = {1963}, pages = {219-221}, zbl = {0117.31401}, mrnumber = {167668}, language = {en}, url = {http://dml.mathdoc.fr/item/BUMI_1963_3_18_3_219_0} }
Bellman, Richard. On the nonnegativity of Green's functions.. Bollettino dell'Unione Matematica Italiana, Tome 18 (1963) pp. 219-221. http://gdmltest.u-ga.fr/item/BUMI_1963_3_18_3_219_0/
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