About chromatic uniqueness of complete tripartite graph $K(s, s - 1, s - k)$, where $k\geq 1$ and $s - k\geq 2$

Let $P(G, x)$ be the chromatic polynomial of a graph $G$. A graph $G$ is called chromatically unique if for any graph $H,\, P(G, x) = P(H, x)$ implies that $G$ and $H$ are isomorphic. In this parer we show that full tripartite graph $K(s, s - 1, s - k)$ is chromatically unique if $k\geq 1$ and $s - k\geq 2$.