What a grouping. I am no expert when it comes to authenticating signatures, markings or other such markings. I do recognize however when things are 'odd' or 'stand out' and these have just that curious intrigue. Some are dated as early as 1903 and as late as 1905. Notations appear to be of a 'cataloging system' possibly. Most of these are cities around the world. Most are in generally used good condition. Some are better. Many many more images available if you have a true interest in the pertinent details. What else would you like to know? Please contact me with any questions, concerns or other issues that you may have. Thanks for your interest.
A lot of fifteen postcards marked Frank A Ruf, F. A. R., a great collection of art and cities around the world.