Serial number of the photograph written by hand on the negative. There is no sequential number printed on the card. Postcards are found with reverse sides with undivided fancy frame (1900-1901), simple undivided back (1902-1906) and divided back (1906 and later). Many cards have the publisher's name printed on the front side and back. Few cards were hand colored.

These black & white, sequentially numbered postcards can also be found very rarely in color. There is no publisher listed in the majority of the postcards.

These cards were printed by the printing company Mehner and Maas, Leipzig.

The serial numbers given in the title are Mehner and Maas serial numbers and are not assigned by Ludwigsohn. They are sometimes found in the front of the card, other times on the back middle or left-bottom.

These postcards were printed in Frankfurt Germany by Rosenblatt Lithografische Kunstanstalt company (serial number found on the back of the card is part of the card's name - i.e. L-B12780 has the number 12780 in the back over the stamp box area).

Rosenblatt was specialized in the production of picture postcards as well as congratulation cards by chromolitho process. Rosenblatt closed down by early 1909 as a result of the US protective tariffs.