[1] FOLTÝNSKA I., WERBOWSKI J.: On the oscillatory behaviouг of solutions of system of diffeгential equations with deviating aгguments. Colloquia Math. Soc. J. B. 30, Oualitative theoгy of Diff. Eq. Szeged, 1979, 243-256.
[2] KITAMURA Y., KUSANO T.:
Oscillation and a class of nonlinear diffeгential systems with geneгal deviating aгguments. Nonlineaг Analysis, Theoгy, Methods and Appl. Vol. 2, No. 5, 1978, 337-351.
MR 0512150
[3] KITAMURA Y., KUSANO T.:
Asymptotic pгopeгties of solutions of two-dimensional diffeгential systems with deviating argument. Hiroshima Math. J. 8, 1978, 305-326.
MR 0492742
[4] KITAMURA Y., KUSANO T.:
On the oscillation of a class of nonlineaг diffeгential systems with deviating argument. J. Math. Anal. Appl. 66, 1978, 20-36.
MR 0513483
[5] KITAMURA Y., KUSANO T.:
Nonlineaг oscillation of higheгoгder functional differential equations with deviating arguments. J. Math. Anal. Appl. 77, 1980, 100-119.
MR 0591264
[6] MARUŠIAK P.:
On the oscillation of nonlinear differential systems with retarder arguments. Math. Slovaca 34, No. 1, 1984, 73-88.
MR 0735938
[7] OЛEXHИК C. H.: O кoлeблeмocти peшeний нeкoтopoй cиcтeмы oбыкнoвeнныx диффepeнциaльныx ypaвнeний втopoгo пopядкa. Дифф. ypaв. 9, № 12, 1973, 2146-2151.
[8] ШEBEЛO B. H., BAPEX H. B., ГPИЦAЙ A. Г.: Oб ocциллятopныx cвoйcтвax peшeний cиcтeм диффepeнциaльныx ypaвнeний c зaпaздывaющим apгyмeнтoм. Ин-т мaтeмaтики AH УCCP, Киeв 1982.
[9] BAPEX H. B., ШEBEЛO B. H.: Oб ycлoвияx ocцилляции peшeний cиcтeм диффepeнциaльныx ypaвнeний c зaпaздывaющим apгyмeнтoм. B кн. Кaчecтвeнныe мeтoды тeopии диффepeнциaльныx ypaвнeний c oтклoняющимcя apгyмeнтoм. Ин-т мaтимeтики AH УCCP, Киeв 1977, 26-46.