If they are generic, such as most of what I collect, they rarely have a catalog or ACC number. Burdick was big on postcards so there are a lot of ACC numbers we rarely use for the sets we talk about. Also, one of our members dad's, Dr Lowe, was the king of postcards in the day. He wrote the book on them as Burdick did our other cards...
Dr, James Lowe invented the term deltiology (study of postcards) and has books and a ton of information out there. Good luck...
And a PC750, generic postcard...
