  For $m \geq 3$ and $n \geq 1$, the $m$-cycle book graph $B(m,n)$ consists of
$n$ copies of the cycle $C_m$ with one common edge. In this paper, we prove
that (a) the number of switching non-isomorphic signed $B(m,n)$ is $n+1$, and
(b) the chromatic number of a signed $B(m,n)$ is either 2 or 3. We also obtain
explicit formulas for the chromatic polynomials and the zero-free chromatic
polynomials of switching non-isomorphic signed book graphs.

Combinatorics