  Let $G=(V,E)$ be a simple graph. A dominating set of $G$ is a subset
$S\subseteq V$ such that every vertex not in $S$ is adjacent to at least one
vertex in $S$. The cardinality of a smallest dominating set of $G$, denoted by
$\gamma(G)$, is the domination number of $G$. A dominating set $S$ is called a
super dominating set of $G$, if for every vertex $u\in \overline{S}=V-S$, there
exists $v\in S$ such that $N(v)\cap \overline{S}=\{u\}$. The cardinality of a
smallest super dominating set of $G$, denoted by $\gamma_{sp}(G)$, is the super
domination number of $G$. In this paper, we obtain more results on the super
domination number of graphs which is modified by an operation on vertices.
Also, we present some sharp bounds for super domination number of chain and
bouquet of pairwise disjoint connected graphs.
