[1] Vlček V.:
On a distribution of zeros of solutions of a fourth-order iterated linear differential equation. (Acta UP Olom., F. R. N., Tom 57, 1978).
MR 0554040 |
Zbl 0422.34037
[2] Borůvka O.:
Lineare Differentialtransformationen 2. Ordnung. (VEB Deutscher Verlag der Wissenschaften, Berlin, 1967).
MR 0236448
[3] Vlček V.:
On functions describing a distribution of zeros of solutions of an iterated linear differential equation of the fourth order. (Acta UP Olom., F.R.N., 1979).
MR 0589852 |
Zbl 0452.34028