Remarks on the Symmetry lie Algebras of first Integrals of Scalar third Order Ordinary Differential Equation with Maximal Symmetry G. R. Flessas (1994) Δελτίο της Ελληνικής Μαθηματικής Εταιρίας
Renormalization of cocycles and linear ODE with almost-periodic coefficients. Marek Rychlik (1992) Inventiones mathematicae