Construction of a system of linear differential equations from a scalar equation

D. V. Anosov and A. A. Bolibruch, The Riemann-Hilbert Problem (Vieweg, Braunschweig, 1994), Aspects Math. 22. W. Balser, W. B. Jurkat, and D. A. Lutz, “A General Theory of Invariants for Meromorphic Differential Equations. I: Formal Invariants,” Funkc. Ekvacioj 22(2), 197–221 (1979). A. A. Bolibrukh, The 21st Hilbert Problem for Linear Fuchsian Systems (Nauka, Moscow, 1994), Tr. Mat. Inst. im. V.A. Steklova, Ross. Akad. Nauk 206 [Proc. Steklov Inst. Math. 206 (1995)]. A. A. Bolibrukh, Inverse Monodromy Problems in the Analytic Theory of Differential Equations (MTsNMO, Moscow, 2009) [in Russian]. A. A. Bolibruch, S. Malek, and C. Mitschi, “On the Generalized Riemann-Hilbert Problem with Irregular Singularities,” Expo. Math. 24, 235–272 (2006). W. Wasow, Asymptotic Expansions for Ordinary Differential Equations (Interscience, New York, 1965; Mir, Moscow, 1968). M. van der Put and M.-H. Saito, “Moduli Spaces for Linear Differential Equations and the Painlevé Equations,” Ann. Inst. Fourier 59(7), 2611–2667 (2009). R. R. Gontsov, “Refined Fuchs Inequalities for Systems of Linear Differential Equations,” Izv. Ross. Akad. Nauk, Ser. Mat. 68(2), 39–52 (2004) [Izv. Math. 68, 259–272 (2004)]; “Letter to the Editors,” Izv. Ross. Akad. Nauk, Ser. Mat. 68 (6), 221–222 (2004) [Izv. Math. 68, 1277–1279 (2004)]. P. Deligne, Equations différentielles à points singuliers réguliers (Springer, Berlin, 1970), Lect. Notes Math. 163. B. Malgrange, “Sur les points singuliers des équations différentielles,” Enseign. Math. 20, 147–176 (1974). P. Hartman, Ordinary Differential Equations (J. Wiley and Sons, New York, 1964; Mir, Moscow, 1970). W. B. Jurkat and D. A. Lutz, “On the Order of Solutions of Analytic Linear Differential Equations,” Proc. London Math. Soc. 22(3), 465–482 (1971).