@article {fonda2012, title = {Periodic solutions of a system of coupled oscillators with one-sided superlinear retraction forces}, journal = {Differential Integral Equations}, volume = {25}, number = {11/12}, year = {2012}, month = {11}, pages = {993{\textendash}1010}, publisher = {Khayyam Publishing, Inc.}, url = {https://projecteuclid.org:443/euclid.die/1356012248}, author = {Alessandro Fonda and Andrea Sfecci} }