Peter Hillel Berman

Berman, P. H., & Singer, M. F. (1999, June 17). Calculating the Galois group of L-1(L-2(y))=0, L-1,L-2 completely reducible operators. JOURNAL OF PURE AND APPLIED ALGEBRA, Vol. 139, pp. 3–23. https://doi.org/10.1016/S0022-4049(99)00003-1