On the oscillation of solutions of a class of linear fourth order differential equations Ján Regenda — 1983 Czechoslovak Mathematical Journal
Oscillation theorems for a class of linear fourth order differential equations Ján Regenda — 1984 Czechoslovak Mathematical Journal
On some properties of third-order linear differential equation Ján Regenda — 1976 Mathematica Slovaca
A note on oscillation and nonoscillation criteria for fourth order linear differential equations Ján Regenda — 1983 Mathematica Slovaca
Oscillation criteria for fourth-order linear differential equations Ján Regenda — 1979 Mathematica Slovaca
Oscillation criteria for differential equation y ( 4 ) + P ( t ) y ' ' + R ( t ) y ' + Q ( t ) y = 0 Ján Regenda — 1984 Mathematica Slovaca
Oscillatory and nonoscillatory properties of solutions of the differential equation y ( 4 ) + P ( t ) y " + Q ( t ) y = 0 Ján Regenda — 1978 Mathematica Slovaca