@article{ZNSL_1989_176_a2,
     author = {D. Yu. Grigor'ev},
     title = {Complexity of factoring and {GCD} calculating for linear ordinary differential operators},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {68--103},
     publisher = {mathdoc},
     volume = {176},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1989_176_a2/}
}