Scalar perturbations in cosmological f(R) models: the cosmic screening approach Özgür Akarsu, Ruslan Brilenkov, Maxim Eingorn, Valerii Shulga and Alexander Zhuk Eur. Phys. J. C, 78 8 (2018) 609 Published online: 30 July 2018 DOI: 10.1140/epjc/s10052-018-6091-7