Let $\mathcal {N}_G$ denote the set of all proper
normal subgroups of a group $G$ and $A$ be an element of $\mathcal
{N}_G$. We use the notation $ncc(A)$ to denote the number of
distinct $G$-conjugacy classes contained in $A$ and also $\mathcal
{K}_G$ for the set $\{ncc(A)\ |\ A\in \mathcal {N}_G\}$. Let $X$ be
a non-empty set of positive integers. A group $G$ is said to be
$X$-decomposable, if $\mathcal {K}_G=X$. In this paper we give a
classification of finite $X$-decomposable groups for $X=\{1, 2, 3,
4\}$.
Guo, X., & Chen, R. (2014). On finite $X$-decomposable groups for $X=\{1, 2, 3, 4\}$. Bulletin of the Iranian Mathematical Society, 40(5), 1243-1262.
MLA
Guo, X., & Chen, R. "On finite $X$-decomposable groups for $X=\{1, 2, 3, 4\}$", Bulletin of the Iranian Mathematical Society, 40, 5, 2014, 1243-1262.
HARVARD
Guo X., Chen R. (2014). 'On finite $X$-decomposable groups for $X=\{1, 2, 3, 4\}$', Bulletin of the Iranian Mathematical Society, 40(5), pp. 1243-1262.
CHICAGO
X. Guo & R. Chen, "On finite $X$-decomposable groups for $X=\{1, 2, 3, 4\}$," Bulletin of the Iranian Mathematical Society, 40 5 (2014): 1243-1262,
VANCOUVER
Guo X., Chen R. On finite $X$-decomposable groups for $X=\{1, 2, 3, 4\}$. BIMS. 2014;40(5):1243-1262.
