Prussian directories

[still_looking]

Hello,

I'm in the process of trying to verify some information that has been hand-written on a mounted photograph.

The text goes something like :

Photographischet Atelier von Julius Krüger in Stralsund

The text claims that the photo is from 1864.

This isn't a cdv or portrait so there isn't the usual photographer's details on the back or front of the card.

Does anyone know of a suitable directory or source where I can find out more about this photographer (address etc.?).

Thanks in advance.

S_L