@article{Grigorenko_2009, title={Algebraic-geometric operators and Galois differential theory}, volume={61}, url={https://umj.imath.kiev.ua/index.php/umj/article/view/2997}, abstractNote={We show that, by using the Galois differential theory, one can substantially improve the description of algebraic-geometric operators. In particular, we give a complete description of all elementary algebraic-geometric operators, present simple relations for the construction of all second-order operators of this type, and give a criterion for testing the algebraic-geometric properties of a linear differential operator with meromorphic coefficients.}, number={1}, journal={Ukrainsâ€™kyi Matematychnyi Zhurnal}, author={Grigorenko, N. V.}, year={2009}, month={Jan.}, pages={14-27} }