Li, J., Luo, J. and Wang, Z. 2015. Retraction notice to “Periodic Solutions of Second Order Impulsive Differential Equations at Resonance via Variational Approach” [Math. Model. Anal. 19(5):664–675, 2014]. Mathematical Modelling and Analysis. 20, 2 (Mar. 2015), 289. DOI:https://doi.org/10.3846/13926292.2015.1024973.