Hamiltonian cycle in the power graph of direct product two p-groups pf prime exponents

The power graph P(G) of a finite group G is a graph whose vertex set is the group G and distinct elements x; y are adjacent if one is a power of the other. Suppose that G = P * Q, where P (resp. Q) is a finite p-group (resp. q-group) of exponent p (resp. q) for distinct prime numbers p < q. In this paper, we determine necessary and sufficient conditions for existence of Hamiltonian cycles in P(G).