@article{120059,
author = {Vladim\'\i r Vl\v cek},
title = {On a distribution of zeros of solutions of a fourth-order iterated linear differential equation},
journal = {Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica},
volume = {17},
year = {1978},
pages = {85-108},
zbl = {0422.34037},
mrnumber = {0554040},
language = {en},
url = {http://dml.mathdoc.fr/item/120059}
}
Vlček, Vladimír. On a distribution of zeros of solutions of a fourth-order iterated linear differential equation. Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica, Tome 17 (1978) pp. 85-108. http://gdmltest.u-ga.fr/item/120059/
Properties of solutions of $N^{\text th}$ order linear differential equations, Pacific J. Math., Vol. 15, No. 3, 1965. (1965) | MR 0185185
Lineare Differentialtransformationen 2. Ordnung, VEB Deutscher Verlag der Wissenschaften, Berlin, 1967. (1967) | MR 0236448