Differ. Uravn., 1974 Volume 10, Number 3,Pages 379–408(Mi de2114)
Ordinary Differential Equations
Analytic and qualitative theory, and also asymptotic behavior of the solutions of the system of equations $\frac{dx}{dz}=\frac1{z}\sqrt{xy(x+y)}$, $\frac{dy}{dz}=\frac1{1-z}\sqrt{xy(x+y)}$