@article {2016,
	title = {Pairs of positive periodic solutions of nonlinear ODEs with indefinite weight: a topological degree approach for the super-sublinear case},
	journal = {Proc. Roy. Soc. Edinburgh Sect. A 146 (2016), 449{\textendash}474.},
	number = {Proceedings of the Royal Society of Edinburgh. Section A. Mathematics;volume 146; issue 3; pages 449-474;},
	year = {2016},
	note = {AMS Subject Classification: Primary 34B18; 34C25; Secondary 34B15; 47H11;},
	publisher = {Cambridge University Press},
	abstract = {<p>We study the periodic and Neumann boundary value problems associated with the second order nonlinear differential equation u{\textquoteright}{\textquoteright}+cu{\textquoteright}+λa(t)g(u)=0, where g:[0,+$\infty$[{\textrightarrow}[0,+$\infty$[ is a sublinear function at infinity having superlinear growth at zero. We prove the existence of two positive solutions when ∫a(t)dt 0 is sufficiently large. Our approach is based on Mawhin{\textquoteright}s coincidence degree theory and index computations.</p>},
	doi = {10.1017/S0308210515000621},
	url = {http://urania.sissa.it/xmlui/handle/1963/35262},
	author = {Alberto Boscaggin and Guglielmo Feltrin and Fabio Zanolin}
}
