@article{1256054114, author = {Kreith, Kurt}, title = {Criteria for positive Green's functions}, journal = {Illinois J. Math.}, volume = {12}, number = {4}, year = {1968}, pages = { 475-478}, language = {en}, url = {http://dml.mathdoc.fr/item/1256054114} }
Kreith, Kurt. Criteria for positive Green's functions. Illinois J. Math., Tome 12 (1968) no. 4, pp. 475-478. http://gdmltest.u-ga.fr/item/1256054114/