Barotov, D. N., and R. N. Barotov. “On One Criterion of Expressibility of Functions of a System of Linear Differential Equations With Constant Coefficients in the Form of Linear Combinations of Derivatives of One Function Included in This System”. Numerical Methods and Programming (Vychislitel’nye Metody I Programmirovanie), vol. 24, July 2023, pp. 260-74, doi:10.26089/NumMet.v24r319.