  A neighborhood-prime labeling of a graph is a variation of a prime labeling
in which the vertices are assigned labels from $1$ to $|V(G)|$ such that the
$\gcd$ of the labels in the neighborhood of each non-degree $1$ vertex is equal
to $1$. In this paper, we examine neighborhood-prime labelings of several
classes of graphs such as polygonal snakes and books, with a focus on trees
including caterpillars, spiders, and firecrackers.
