Scalar and vector perturbations in a universe with nonlinear perfect fluid Ezgi Canay, Ruslan Brilenkov, Maxim Eingorn, A. Savaş Arapoğlu and Alexander Zhuk Eur. Phys. J. C, 81 3 (2021) 246 Published online: 21 March 2021 DOI: 10.1140/epjc/s10052-021-09032-9