Abelian Groups that are unions of proper subgroups
K. P. S. Bhaskara Rao, James D. Reid · Bulletin of the Australian Mathematical Society · 1992
The abelian groups that can be written as a union of proper subgroups are characterised, all the ways that this can be done for a given group are indicated, and the minimal number of subgroups necessary for such a decomposition of a given group is determined.