  Given a graph $G$ with a total order defined on its vertices, the Maximum
Pagenumber-$k$ Subgraph Problem asks for a maximum subgraph $G'$ of $G$ such
that $G'$ can be embedded into a $k$-book when the vertices are placed on the
spine according to the specified total order. We show that this problem is
NP-complete for $k \geq 2$.
