  For a $k$-algebra $A$, a quiver $Q$, and an ideal $I$ of $kQ$ generated by
monomial relations, let $\Lambda: = A\otimes_k kQ/I$. We introduce the monic
representations of $(Q, I)$ over $A$. We give properties of the structural maps
of monic representations, and prove that the category ${\rm mon}(Q, I, A)$ of
the monic representations of $(Q, I)$ over $A$ is a resolving subcategory of
${\rm rep}(Q, I, A)$. We introduce the condition ${\rm(G)}$. The main result
claims that a $\m$-module is Gorenstein-projective if and only if it is a monic
module satisfying ${\rm(G)}$. As consequences, the monic $\m$-modules are
exactly the projective $\m$-modules if and only if $A$ is semisimple; and they
are exactly the Gorenstein-projective $\m$-modules if and only if $A$ is
selfinjective, and if and only if ${\rm mon}(Q, I, A)$ is Frobenius.
