Pinelas, Sandra (ed.) et al., Differential and difference equations with applications. Contributions from the international conference on differential and difference equations and applications in honour of Ravi P. Agarwal, Ponta Delgada, Portugal, July 4–8, 2011. New York, NY: Springer (ISBN 978-1-4614-7332-9/hbk; 978-1-4614-7333-6/ebook). Springer Proceedings in Mathematics & Statistics 47, 375-385 (2013).