I haven’t yet dug up descriptors and attribution language for all these photos, and I apologize to the photographers whose work I haven’t yet credited. In the meantime, I’d say that with the exception of the Sarah Weishaupt illustration, these are all almost certainly freely-licensed and therefore safe for you to reuse without requesting permission from the copyright holder. If you reuse photos that have attribution, please include it in your republished work. If you reuse a photo that doesn’t have attribution information, you may be able to find it by doing a reverse image search at TinEye or browsing Wikimedia Commons. Feel free to crop, resize, etc.