 Precisely in the same years similar attempts to formulate a relativistic generalization of Bohmian Mechanics were ongoing, encountering difficulties. Relevant steps are represented by a paper (Dürr 1999) resorting to a preferred spacetime slicing, by the investigations of Goldstein and Tumulka (2003) and by other scientists (Berndl et al. 1996). However, we must acknowledge that no one of these attempts has led to a fully satisfactory solution of the problem of having a theory without observers, like Bohmian mechanics, which is perfectly satisfactory from the relativistic point of view, precisely due to the fact that they are not genuinely Lorentz invariant in the sense we have made precise before. Mention should be made also of the attempt by Horton and Dewdney (2001) to build a relativistically invariant model based on particle trajectories. 