LI, Jin; LUO, Jianlin; WANG, Zaihong. 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, [S. l.], v. 20, n. 2, p. 289, 2015. DOI: 10.3846/13926292.2015.1024973. Disponível em: https://journals.vilniustech.lt/index.php/MMA/article/view/1000. Acesso em: 2 jun. 2025.