%0 Journal Article %A E. I. Bravyi %T On necessary conditions for the negativity of the Green function for a two-point problem %J Izvestiâ vysših učebnyh zavedenij. Matematika %D 2001 %P 12-22 %N 6 %U http://geodesic.mathdoc.fr/item/IVM_2001_6_a1/ %G ru %F IVM_2001_6_a1