I am reading Masur's paper *On a class of geodesic in Teichmuller space*. He mentions that $T(S_0)$ where $S_0$ is a closed Riemann surface $g\geq2$ is **straight**, i.e. **uniquely geodesic**. It seems a well-known result, but as I am a beginner I am trying to prove it with the Teichmuller theorem at my disposal. Now I can prove that each $(k,\phi)$, where $k$ varies in $(-1,1)$ and $\phi$ is a fixed holomorphic quadratic differential, is a geodesic. But I don't know how to go on and prove that this is unique.

Also, the books/articles I've been reading point me to Kravetz's *On the geometry of Teichmuller spaces and the structure of their modular group*. But I can't find it anywhere online. Does anyone know where to look for this paper?