Dealing with copyright issues

I try not to include images in this blog that are or may be copyrighted. In cases where copyright may be an issue, I construct an image like above, consisting of a picture of a magnifying glass and a thumbnail of the image I want to share (at the location of the copyright symbol in the image above). The magnifying glass image is sourced from Openclipart (link), which comes with a statement that all clip art available on the site is in the public domain. By keeping the thumbnail at a size smaller than 125 pixels (largest side), the thumbnail is deemed acceptable as fair use. If the blog reader clicks on the image, he or she will be taken to the page from which I retrieved the image (e.g. an artist's web site) to see it in normal size.