Solvability of singular boundary value problems for ordinary differential equations of order 2 m . Yakovlev, M.N. — 2004 Zapiski Nauchnykh Seminarov POMI
Existence of nonnegative solutions of singular boundary-value problems for second-order ordinary differential equations. Yakovlev, M.N. — 2005 Zapiski Nauchnykh Seminarov POMI