Always be aware of copyright issues, never assume the lack of notice for copyright means it is not protected. When you are using any images which you plan to publish, be sure to ask for permission from the original source. You can contact the original creator and ask for legal permission. There are many royalty free sites that you may access to obtain images without the threat of copyright issues. You may also come across some photos that say “unequivocal Language” this means the author is giving up all the rights to his work, and is allowing you to use the information freely.