@article{MAT_1957_1_2_a2,
     author = {H. L. Turrittin},
     title = {Asymptotic expansion of solutions of systems of ordinary linear differential equations containing a parameter},
     journal = {Matematika},
     pages = {29--60},
     publisher = {mathdoc},
     volume = {1},
     number = {2},
     year = {1957},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MAT_1957_1_2_a2/}
}