  The Klein-Gordon equation is solved for di-Holeums (gravitational bound
states of two micro black holes) for scalar and vector gravity in its static
limit. The relativistic models confirm the predictions of the nonrelativistic
Newtonian gravity model, correct to about six significant figures over almost
the entire sub-Planck domain. All three models possess a mass range devoid of
physics. This is interpreted as evidence that the universe must have more than
four dimensions. We show that the formation of Holeums is feasible both in the
sub-Planck mass and above-Planck mass ranges.
