An Upper and Lower Solution Theory for the Problem (G'(y))'+f(t, y)=0 on Finite and Infinite Intervals

Ravi P. AGARWAL, Donal O'REGAN, Svatoslav STANĚK

Acta Mathematica Sinica . 2006, (3): 827 -832 . DOI: 10.1007/s10114-005-0635-0