Khusainov, D. Ya., and V. N. Shevelo. “Stability of Differential Systems With Rational Right-Hand Sides”.
Ukrains’kyi Matematychnyi Zhurnal
, vol. 47, no. 9, Sept. 1995, pp. 1295–1299,
https://umj.imath.kiev.ua/index.php/umj/article/view/5530
.