they are solutions of the equation $E^2-V\vphantom{\underline{A}}_{\!\!eff}=0$ such that $r_{\!\scriptscriptstyle min}< r_{\!\scriptscriptstyle J}< r_{\!\scriptscriptstyle max}$, where $r_{\!\scriptscriptstyle J}$ is a (global or local) minimum of $V\vphantom{\underline{A}}_{\!\!eff}(r,J)$, and there are no other solutions in the interval $(r_{\!\scriptscriptstyle min},r_{\!\scriptscriptstyle max})$. Thus, a bound orbit of the general type oscillates near a stable circular orbit (an oscillation is the motion from pericentre to apocentre and back) and $\varphi_{\!{}_{\scriptscriptstyle osc}}$ is the angle between any two successive pericentre points of the orbit. The relativistic precession of pericentres of bound orbits is considered in [@Meyer2012; @Goddi2017; @Grould2017b; @Vieira2014; @Collodel2018; @Zakharov2012; @Dokuchaev2015; @Zakharov2018] both from a purely theoretical point of view and in the context of observations of S-stars in the Galactic Centre.

If a massive test particle moves radially in some non-static degenerate orbit, which will be the case if $J=0$ and $A(r_0)<E^2<1$, then $\Delta\varphi=-2\pi$. For any small $J\gtrapprox{}0$, this orbit becomes nondegenerate and can have an arbitrarily large number of oscillations per revolution. With further increasing $J$ (and with fixed $E$), the number and the amplitude of oscillations monotonically decrease, while the angle of precession increases and reaches its maximum value. We always have $\Delta\varphi<0$ for orbits located, even if only in part, in 