Hi Myrna, I agree with Doreen and Denise.  You have to be very careful because age of a work alone does not make it free use.  As stated, the surviving members of the family probably have the copyrights. When you are writing a book, this issue is HUGE.  Publishers are extremely cautious and a book can be held up for years until all permissions are granted. With cards here, it seems a small effort to give credit to the original artist. And yes, It must be there embedded in the jpg.  It  takes a little finesse to give the credit without destroying the mood of the image. But I think it's worth it, don't you?  Yes, I know you do.