I'm currently drafting up a licensing agreement for an organization to use some of my images in a slideshow/PowerPoint for a fundraising event. I will be licensing 53 images to them for this sole purpose, but I doubt they will be using ALL 53 images. The organization will also likely be using images from other sources as well in the slideshow. My question is, what is a reasonable method of photo credit to ask for in the licensing agreement? For the number of images that they are using, a specific byline underneath each image would be both tedious for them, as well as potentially aesthetically detrimental to the slideshow. I would be okay with a simple "Images provided by" type of credit on the final slide, but I am not (likely to be) the exclusive image provider for this slideshow, and I don't want it to appear as though I am taking credit for another photographer's work. Any suggestions on how to phrase my credit requirement in the license agreement?