Groups with prescribed systems of Schmidt subgroups

A Schmidt $(p, q)$-group is a Schmidt group $G$ with $\pi(G) = \{p, q\}$ and normal Sylow $p$-subgroup. The $N$-critical graph $\Gamma_{Nc}(G)$ of a group $G$ is the directed graph with the vertex set $\pi(G)$ in which $(p, q)$ is an edge iff $G$ has a Schmidt $(p, q)$-subgroup. The finite groups for which the degrees of vertices of the $N$-critical graph are at most $2$ are studied.