Chiu, K.-S., and I. B. Sepúlveda. “Infinitely Many Periodic Solutions for Differential Equations Involving Piecewise Alternately Advanced and Retarded Argument”. Eurasian Mathematical Journal, vol. 16, no. 4, Dec. 2025, pp. 33-44, doi:10.32523/2077-9879-2025-16-4-33-44.