gravity - Is $F = Gdfrac{{m_1}{m_2}}{r^2}$ really true?

My book (Concepts of Physics by H.C. Verma) writes:

It has been reported (Phys. Rev. Lett. Jan 6, 1986) that the force between two masses is better represented by: $$F = \frac{G_{\infty} m_{1} m_{2}}{r^2} \left[1 + \alpha\left(1 + \frac{r}{\lambda} \right) e^{-r/\lambda}\right]$$ where $\alpha = - 0.007$ & $\lambda = 200m$ .

What is this? Such a horrendous formula! So, what about Newton's one?? And what's the difference between $G$ & $G_{\infty}$??? Please help.