[1] Greguš M.: 
Oszillatorische Eigenschaften der Lösungen der linear Differentialgleichungen dritter Ordnung $y''' + 2Ay' + (A' + b)y = 0$, wo $A = A(x) \leq 0$ ist. Czech. Math. J., 9 (84) (1959), 416-428. 
MR 0111888[2] Greguš M.: 
Über einige Eigenschaften der Lösungen der Differentialgleichungen $y'" + 2Ay' + (A' + b)y = 0, A \leq 0$. Czech. Math. J., 11 (86) (1961), 106-114. 
MR 0131028 |3] Hanan M.: 
Oscillation criteria for third-order linear differential equation. Pacif. J. Math., 11 (1961), 914-944. 
MR 0145160[4] Lazer A. C: 
The behavior of solutions of the differential equation $y''' + p(x) y' + q(x) y = 0$. Pacif. J. Math., 17 (1966), 435-465. 
MR 0193332 | 
Zbl 0143.31501[5] Moravský L.: 
Einige oszillatorische und asymptotische Eigenschaften der Lösungen der Differentialgleichung $y''' + p(x) y" + 2A(x) y' + (A'(x) + b(x)) y = 0$. Acta F. R. N. Univ. Comen.-Mathematica, 16 (1967). 
MR 0240390[6] Neuman F.: 
Geometrical approach to linear differential equations of the n-th order. Rend. di Matem., 5 (1972), 579-602, 
MR 0324141 | 
Zbl 0257.34029[7] Neuman F.: 
Oscillation in linear differential equations. Proceedings of Equadiff III, Brno 1972, 119-125. 
MR 0350114[8] Regenda J.: 
On some properties of third-order linear differential equation. Math. Slov., 26 (1976), 3-18. 
MR 0427742 | 
Zbl 0351.34020[9] Singh Y. P.: 
Some oscillation theorems for third order non-linear differential equations. The Yokohama Math. J., 18 (1970), 77-86. 
MR 0283300 | 
Zbl 0216.36901[10] Singh Y. P.: 
The asymptotic behavior of solutions of linear third order differential equations. Proceedings of the American Math. Society, 20 (1969), 309-314. 
MR 0237885 | 
Zbl 0179.40503[11] Tryhuk V.: 
An oscillation criterion for third order linear differential equations. Arch. Math. Brno, 11 (1975), 99-104. 
MR 0412523[12] Zlámal M.: 
Asymptotic properties of the solutions of the third order differential equations. Publ. Fac. Sci. Univ. Masaryk, 329 (1951), 159-167. 
MR 0057412