Wikimedia
Wikipedia: Rudolf Clausius
This site from the Encyclopedia Wikipedia provides brief biographical information on German physicist and mathematician Rudolf Clausius including an image, hyperlinked terms, and external links.
Wolfram Research
Wolfram Science World: Rontgen, Wilhelm
This site from ScienceWorld provides a very short biographical sketch of Wilhelm Rontgen (1845-1923 CE) and describes his most notable scientific discoveries and contributions.