In the book
S. Wiggins, Introduction to applied nonlinear dynamical systems and chaos. Vol. 2. Springer Science $\&$ Business Media, (2003).
the author recalls a system:
$$\begin{cases} \frac{dx}{dt}&=x^2, \\ \frac{dy}{dt}&=-y, \ \ \ \ \ \ (x,y)\in\mathbb R^2. \end{cases} $$ He attributes this system to Anosov, but the reference is:
J. Sijbrand, Properties of center manifolds. Trans. Amer. Math. Soc. 289, 431–469, 1985.
I'd like to know the original bibliographic source by Anosov in which it appears this system.
Thanks in advance.