If you're looking for images to use in a presentation or report, it can be a real pain to try and find ones that you can grab without legal problems. LibreStock is a free multi search engine that will check through over 40 different websites to find images that you can use. I quote from the site: "I know it's hard to understand complex legal licenses so let me break it down for you. all the photos indexed on LibreStock are licensed under the Creative Commons Zero license. this means you can use these pictures freely for any legal purpose." This means that they are free to use, even commercially, you can modify, copy and distribute, and you don't need to attribute.
That's great - so what about the images themselves? My search for 'books' came back with over 570 images from a variety of sites. A lot of the images however were nothing to do with books, including the one with a woman sitting on some steps looking at a penguin. (Don't ask me, because I don't know!) There were zero results for 'librarian' but everything else I searched for I got something back. There's no specific listing of all the sites that the engine pulls data from, but when you cursor over each image you'll see the source site and tags for each image.
The images are of excellent quality - sharp and of a good size. Lots of variety, b&w, colour and I had the feeling that the vast majority came from professional photographers. Most of the photographs did provide information on who the photographer was - even though you're not obliged to include that information, I know that a lot of people would want to do so.
My main disappointment (indeed my only disappointment) was that it's a fairly small collection. However, it's easy enough to search through, and if you don't find what you want you can easily move onto another site. So if you're looking for excellent imagery, high quality and entirely free for you to do anything you want to with it, this is certainly a site worth looking at.