Needing tips to authenticate prints or posters from 1920-1930

[suzi.ma]

Hi and hello!

I own 12 posters of Mercedes Benz  subject that I am hoping to find out more about.  Mostly hoping to have an expert In the field authenticate as original prints if that is what they are.  Any ideas how and where to head for this process?  

Thanks if you can assist in pointing me in a direction 😊