planarity of inclusion graph of cyclic subgroups of finite group

Let g be a finite group. the inclusion graph of cyclic subgroups of g, ic(g), is the (undirected) graph with vertices of all cyclic subgroups of g, and two distinct cyclic subgroups ‹a› and ‹b›, are adjacent if and only if ‹a› ⊂ ‹b› or ‹b› ⊂ ‹a›. in this paper, we classify all finite abelian groups, whose inclusion graph is planar. also, we study planarity of this graph for finite group g, where |π(z(g))| ≥ 2.