Error during command authentication.

I have several inquiries originating from a student who is enrolled in a course, "The Business of 19th Century Photography." Any help that you can provide or point me to would be greatly appreciated!  

He has already located several sources and has found bits and pieces (nothing substantial) in other sources. Specifically, he is looking for a list of photographers or photographs that were on display during the Paris Salon of 1859 in Ponce, Puerto Rico, where the painters Oscar Rejlander and the Henry Peach Robinson were on display. He is trying to make connections between photographers that may have drawn inspiration from these two other artists, among others exhibited there. Additionally, he would welcome sources that detail the work of art photographers working more broadly during the 1860s in Puerto Rico, as opposed to those that were photographing the coffee plantations, social situations, Europeans immigrating to PR, the Ponce Art Fair, etc.

We've been able to provide him with several resources, but have come to a dead end over here.

Thank you in advance,