Sharp bounds of logarithmic coefficients for a class of univalent functions

Let $\mathcal{U(\alpha, \lambda)}$, $0<\alpha <1$, $0 < \lambda <1$ be the class of functions $f(z)=z+a_{2}z^{2}+a_{3}z^{3}+\cdots$ satisfying $$\left|\left(\frac{z}{f(z)}\right)^{1+\alpha}f'(z)-1\right|<\lambda$$ in the unit disc ${\mathbb D}$. For $f\in \mathcal{U(\alpha, \lambda)}$ we give sharp bounds of its initial logarithmic coefficients $\gamma_{1},\,\gamma_{2},\,\gamma_{3}.$