question about a photographer

[Formyrotts@xxxxxxx]

Ok, I have a name I googled but didn't find anything right away (at least nothing I recognised as info on a photographer I am curious about.  Can anyone help me with the name Ullstein Nicolai?  I have a rectangular frame with 6 photos in it, all musicians, Mozart, Beethoven, Schubert, Wagner, Mendelssohn, and Hadn.  They are actual photos taken by Mr. Nicolai.  The frame looks old as does the back to it, the photos are actual photos, and I am wondering if this gentleman was well known, and I would like to find out a bit about his history.  Any help or pointing me in any direction would be greatly appreciated.  Thanks :)  Linda