David Lawrence lists two 3/3 RPDs for 1903-O, one of which appears in Cherrypickers.
https://archive.org/details/compgui...n73/mode/1up. There may be some new ones published in the next edition, not sure.
Variety Vista lists a few
Barber dime varieties but nothing for 1903-O.
http://varietyvista.com/19th%20Cent...arieties.htmKevin Flynn has a book "The Authoritative Reference on
Barber dimes", I have not seen it but it's supposed to be all RPDs RPMs etc but nothing about mintages or values etc. The best reference to me is Bowers' Guidebook of Barber Silver Coins, but it doesn't have a lot of varieties. I think 1901-O over horizontal O is probably the most famous one.
There are a bunch of design transition varieties 1899-1905, particularly from San Francisco, which I have extensively researched but nobody really cares. I find them more interesting than all the repunches but that's just me. Look for my topic on here under the main US Classic forum if you're interested.