In some synagogues I have seen the amud (lectern) from where the chazan (prayer leader) stands to say the prayers, placed a few feet in front of the aron (cabinet) where the torah is kept or between the aron and the bima (reading table). In other synagogues I have also seen the amud placed a few feet to the right of the aron. Is there an exact location where the amud should be placed? Does it change location depending on its use? Where can I find this information for further study?