Couchouron, J.-F., M. I. Kamenskii, B. Mikhaylenko, i P. Nistri. „Periodic Bifurcation Problems for Fully Nonlinear Neutral Functional Differential Equations via an Integral Operator Approach: The Multidimensional Degeneration Case”. Topological Methods in Nonlinear Analysis, t. 46, nr 2, grudzień 2015, s. 631-64, doi:10.12775/TMNA.2015.062.