@article{article815a5e66,
title   = {First-order perturbation for multi-parameter center families},
author = {Itikawa, Jackson and Oliveira, Regilene Delazari dos Santos and Torregrosa, Joan},
year = {2022},
doi = {10.1016/j.jde.2021.11.035},
journal   = {Journal of Differential Equations}
}