d-dominating sets in graphs are very important in wireless hierarchical networks. In the first part, the paper simplifies and extends the heuristic proposed in [APVH00] and then proves the correctness of the extended heuristic which forms d-dominating sets. This clusterhead selection process has the advantage of being distributed and scalable. In the second part, the cluster formation process proposed in [APVH00] is extensively studied, by using the analysis mathematical framework developed in the first section. It is proved that the heuristic presented in [APVH00] is not always valid. This is a very important result since the Max-Min d-cluster formation is a well known heuristic and a very interesting one to select clusterheads under a given criterion