Maybe somebody can point me in the right direction.
With CRM Rest Builder (v2.6.0.0) I get a bad request. I am doing the following:

This is the result:

I tried numerous of options (the ID to retrieve is of course ok), but still a bad request. In the URL this has been added and (i think) is the part that does not work: &$expand=bbpggm_typeid($select=bbpggm_documenttypeid,bbpggm_formuliertypeid)",